Green Century Balanced Fund (GCBLX) N-CSRCertified annual shareholder report (management investment company)

		ANNUAL REPORT Green Century Balanced Fund Green Century Equity Fund Green Century MSCI International Index Fund July 31, 2020

An investment for your future.^®114 State Street, Boston, Massachusetts 02109

For information on the Green Century Funds^®, call 1-800-93-GREEN. For information on how to open an account and account services, call 1-800-221-5519 8:00 am to 6:00 pm Eastern Time, Monday through Friday. For share price and account information, visit www.greencentury.com.

Dear Green Century Funds Shareholder:

I am pleased to report that all three of the Green Century Funds outperformed their benchmarks in the quarter that ended June 30, 2020. You can read more about the Funds’ performance in the attached Annual Report.

As a Green Century investor, you are part of a growing number of individuals interested in environmentally-responsible investing. While responsible investing is increasingly common, Green Century remains unique.

Our three-pronged approach offers investors an unparalleled opportunity to make an environmental impact while seeking competitive financial returns.

What makes us unique?

Green Century invests in sustainable companies

Value-based screens

The Green Century Funds are entirely fossil fuel free. All of the Green Century Funds are prohibited—by prospectus—from investing in companies that explore for, extract, process, refine, and transmit coal, oil, or gas; burn fossil fuels to make electricity; or possess carbon reserves.

As the first family of fossil fuel free, diversified, and responsible mutual funds in the U.S., we have championed fossil fuel divestment since before the divestment movement was launched in 2012.

We continue to play an important role, frequently demonstrating the potential financial benefits—including better performance, lower volatility, and avoidance of stranded assets—of fossil fuel free investing. In April, in commemoration of the 50th anniversary of Earth Day, I was honored to be part of an Environment America web panel on fossil fuel free investing with celebrated environmentalist and author Bill McKibben.

Green Century’s sustainable investment strategy excludes more than just fossil fuel companies, too. We also screen out producers of nuclear energy, nuclear weapons, conventional firearms, GMOs (Genetically Modified Organisms), or tobacco.

Environmental, Social, and Governance (ESG) performance ratings

Since Green Century was founded in 1991, we have sought to invest in environmental leaders and other companies that outperform their peers in addressing the most relevant environmental, supply chain, and corporate governance risks in their industries.

The use of ESG performance ratings may reduce risk and may offer financial advantages, too. It also grants investors the peace of mind to know that they’re only supporting corporate leaders in the effort to address the climate crisis, improve supply chain practices, and implement strong governance structures.

While new ESG products continue to launch, our decades of experience provides investors with an authentic and time-tested approach.

Green Century leverages its status as an investor to produce improved corporate environmental practices

Green Century believes that even corporate sustainability leaders have room for improvement, which is why this year we will work with over 100 companies to adopt stronger environmental practices throughout their operations and supply chains. We believe that companies that protect the environment and public health may avoid brand and reputational damage, which can protect shareholder interests.

Green Century’s shareholder advocacy program directly presses corporations to reduce potential investment risks and deliver tangible results.

Already in 2020, Green Century has:

Green Century supports our environmental and public health nonprofit owners

Green Century is the only mutual fund company in the U.S. wholly owned by environmental and public health nonprofit organizations. This means that 100 percent of the profits Green Century Capital Management earns managing our Funds can be used to support their critical work.

This one-of-a-kind ownership structure is integral to our mission and an important way that we help our investors align their investments with their values.

In the last year, Green Century helped fund many of our nonprofit owners’ environmental and public health campaigns—and the campaigns have made real strides.

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For example, the Wildlife over Waste campaign, which aims to ban take-out plastic foam cups and containers to spare birds, fish and other wildlife from the harm caused by needless plastic pollution, has helped convince Maine, Maryland, Vermont, and Oregon to ban polystyrene.

The 100% Renewable Energy campaign, recently honored as a finalist in the Fast Company World Changing Ideas Awards, has helped push six states—Hawaii, California, New Mexico, Washington, New York, and Maine—to adopt 100% zero-carbon electricity legislation. And the campaign continues in Massachusetts, New Jersey, Pennsylvania, North Carolina, Florida, Michigan, Illinois, and Minnesota.

Green Century’s many environmental victories are only possible because of our investors, so thank you for choosing to make an impact with us. We appreciate your support and are always here to answer any questions.

I also encourage you to subscribe to our free, online newsletter. You can sign up by visiting www.GreenCentury.com, emailing us at info@greencentury.com, or calling us at 1-800-934-7336.

Sincerely,

Leslie Samuelrich

President

Green Century Capital Management

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Green Century on the Web

E-News.    For more regular updates on the Green Century Funds and on our advocacy efforts, please consider signing up for our e-newsletter. Call 1-800-934-7336, visit www.greencentury.com, or email info@greencentury.com.

Online Access.    Information on your account is available on our website at www.greencentury.com.    From the home page, click on Access My Account. Shareholders may also perform online transactions on the site. While there, please consider registering for e-delivery of your statements and other Fund documents.

Twitter.    Green Century is on Twitter. Follow us at Twitter.com/Green__Century for a sustainable investor’s perspective on critical issues.

The Green Century Funds’ proxy voting guidelines and a record of the Funds’ proxy votes for the year ended June 30, 2020 are available without charge, upon request, (i) at www.greencentury.com, (ii) by calling 1-800-934-7336, (iii) by sending an e-mail to info@greencentury.com, and (iv) on the Securities and Exchange Commission’s website at www.sec.gov.

The Green Century Funds file their complete schedule of portfolio holdings with the SEC for the first and third quarters of the year on Form N-PORT, Part F. The Green Century Funds’ Forms N-PORT, Part F are available on the EDGAR database on the SEC’s website at www.sec.gov. Copies may be obtained upon payment of a duplicating fee, by writing the SEC’s Public Reference Section, Washington DC 20549-0102 or by electronic request at the following e-mail address: publicinfo@sec.gov. The information on Form N-PORT, Part F may also be obtained by calling us at 1-800-934-7336, or by e-mailing a request to info@greencentury.com.

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MANAGEMENT’S DISCUSSION OF FUND PERFORMANCE

GREEN CENTURY BALANCED FUND

Investment Objective    The Green Century Balanced Fund seeks capital growth and income from a diversified portfolio of stocks and bonds that meet Green Century’s standards for corporate environmental responsibility.

Portfolio Orientation    As of the fiscal year ended July 31, 2020; the Green Century Balanced Fund (the Balanced Fund or the Fund) was diversified in a number of ways. Equity holdings represented 62.9% and

bonds constituted 30.7% of the Fund’s net asset value. The Fund had 6.4% invested in cash, cash equivalents, and other assets, less liabilities. The portfolio managers view equities as the primary source of potential long-term growth, while emphasizing the importance of diversification in seeking to lower volatility. The Fund’s equity holdings were diversified across 68 equity holdings at fiscal year-end, none of which represented more than 3.4% of total net assets. Generally, larger, less-volatile companies constitute larger positions in the Fund’s portfolio than smaller companies. The portfolio managers seek to mitigate risk by investing primarily in companies they believe have demonstrated records of profitability, above-average growth prospects, and reasonable valuations.

As of July 31, the stocks held by the Balanced Fund were also diversified by sector, with (as a percent of total net assets) Technology (18.6%), Healthcare (9.3%), and Industrials (6.7%) as the largest sectors.

In line with its environmental mandate, the Fund had exposure to what Green Century considers environmental leaders in a number of

GREEN CENTURY BALANCED FUND

INVESTMENT BY INDUSTRY (unaudited)

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industries including Healthy Living, Capital Goods, and Transportation. Green Century’s environmental screens keep the Fund out of traditional Energy and Utility companies, while the Fund has broad exposure to Information Technology, Health Care, Financial, Consumer, and Industrial companies.

In addition to its equity exposure to environmental leaders, the Fund invests in designated Green Bonds and designated Social Impact Bonds. The issuers of Green Bonds have indicated that the proceeds from the bonds will be used for environmentally positive goals such as greenhouse gas reduction, climate adaptation, and climate change mitigation. Issuers of designated Social Impact Bonds have indicated that the proceeds from the bonds will be used for projects supporting such issues as poverty alleviation, low-income housing, fair trade, and community development. As of July 31, 19.1% of the total portfolio and 62.5% of the market value of the bonds held in the Fund were designated Green / Sustainable or Social Impact Bonds.

Higher quality, intermediate maturity bonds can typically lower volatility and provide a stable source of income. At fiscal year end, the Balanced Fund held 47 bonds diversified across corporate and government agency issuers. In an effort to dampen volatility, the weighted average maturity (5.21 years) and modified duration (4.11 years) remain in the intermediate-range. The weighted average yield to maturity was 0.99%. All fixed income holdings were investment grade at the time of purchase and remained investment grade through the end of the fiscal year.

Economic Environment.    The rapid spread of Covid-19 upended all predictions about the year’s stock and bond market returns. In February and March, first the specter, and then the reality, of worldwide pandemic crushed both equity markets and bond markets, exposing fault lines of illiquidity running throughout and between markets. Disruption in Asian supply chains, followed closely by a dramatic shutdown of activity in Europe, swept away our late-2019 expectations for calm markets and improving economic growth in 2020.

In addition, economic and travel shutdowns cratered the demand for oil, which led Saudi Arabia and Russia, unable to agree on a supply cut, to instead increase supply. The price war, designed to drive marginal oil producers, such as U.S. shale oil producers, out of business, compounded the economic damage. Investors scrambled for safety, but many found that their holdings were immeasurably less liquid than they had believed. Investors who were unable to sell what they wanted to sell then moved on to sell what they could sell, pushing waves of selling from the stock market to corporate credit, U.S. Treasuries, and money markets.

Bond market trading seized up, further exacerbated by the actions of exchange traded funds (ETFs), leveraged ETFs, and hedge funds forced to sell holdings at any price to meet liquidations. Even the U.S. Treasury market, generally thought of as the world’s most liquid market, ground to a halt, exposing orders-of-magnitude less dealer support and market making activity than during the Great Financial Crisis. The U.S. Federal Reserve unleashed massive monetary policy measures to support market liquidity, while the Congress enacted an initial fiscal policy response amounting to over 10% of the 2019 level of GDP, which cushioned the immediate economic damage from enforced shutdowns of economic activity. Markets staged a remarkable comeback between April and July, with many indications of improving economic conditions, particularly in countries and regions that were able to reopen safely.

The big questions are whether reopening will lead to sustained economic activity, to what degree we may have an economic backlash due to job losses and government budget constraints, and if the resurgence in

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illness and deaths we are currently seeing continues unabated without mitigation by an effective vaccine. Lastly, the outcome of the upcoming U.S. Presidential election very likely has a profound impact on both the direction and scale of the massive monetary and fiscal policies currently supporting the economic environment.

Investment Strategy and Performance.    Green Century believes that strong environmental, social, and governance practices may enhance corporate profitability and reduce certain types of risks. We specifically avoid risks associated with investments in fossil fuels. Green Century and the Fund’s subadvisor believe that companies with strong balance sheets, strategic leadership in their products and markets, and strong environmental, social, and governance policies will have the financial flexibility and leadership wisdom to navigate choppy and volatile economic conditions.

The Balanced Fund holds a number of stocks which the portfolio managers believe have attractive environmental, social, and financial characteristics. New holdings over the reporting period include AstraZeneca¹ and salesforce.com.¹ AstraZeneca is a leading pharmaceutical company with a focus on oncology, cardiovascular health, and vaccines, including a new partnership with Oxford to develop a coronavirus vaccine. Salesforce.com produces a cloud-based customer relationship management software widely used by a variety of large companies, with a commitment to renewable energy and lower energy use in its datacenters.

The Fund holds over $59 million in Green / Sustainability or Social Impact Bonds and Notes, including notes issued by Apple,¹ The Korea Development Bank,¹ International Finance Corp.,¹ International Bank for Reconstruction and Development (World Bank),¹ U.S. International Development Finance Corp. (which until January 2020 was named the Overseas Private Investment Corp. or OPIC),¹ Starbucks,¹ and Enterprise Community Loan Fund.¹

For the year ended July 31, 2020, the Balanced Fund’s returns were 8.19%, underperforming the 9.97% return for its Custom Balanced Index,² an index comprised of the S&P 1500 Index³ (60% weighting) and of the BofA Merrill Lynch 1-10 Year US Corporate and Government Index⁴ (40% weighting). The underperformance of the Fund during this time period is primarily reflective of a cash drag in the fixed income portion of the portfolio as bonds rallied.

The Fund’s exposure to payment company PayPal¹ for the twelve-month period helped provide strong relative returns in Technology, as did semiconductor equipment exposure from ASML.¹ In Communication Services, the Fund saw above market performance from Alphabet¹ and the New York Times.¹ The Fund’s Financials exposure detracted from relative performance over the year, particularly regional bank KeyCorp,¹ as well as insurance company Travelers.¹ The Fund’s high-quality fixed income exposure performed relatively in-line with the benchmark as designed, although with some underperformance from the Fund’s lack of exposure to Treasuries.

The portfolio managers do not anticipate any significant changes in investment strategy for the Fund, believing that the investment environment may be favorable to the Fund’s core holdings in what the portfolio managers consider high-quality, environmentally responsible companies with strong growth prospects and reasonable valuations.

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* The performance data quoted represents past performance and is not a guarantee of future results. Investment return and principal value of an investment will fluctuate so that an investor’s shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance information quoted. To obtain Fund prices and performance information as of the most recent month-end, call 1-800-93-GREEN/1-800-934-7336. Performance includes the reinvestment of income dividends and capital gain distributions. Performance shown does not reflect the deduction of taxes that a shareholder might pay on Fund distributions or the redemption of Fund shares. A redemption fee of 2.00% may be imposed on redemptions or exchanges of shares you have owned for 60 days or less. Please see the prospectus for more information.

The Balanced Fund consistently includes stocks and bonds of what Green Century believes to be environmentally responsible corporations of various sizes, including small, medium, and large companies. The value of the stocks held in the Balanced Fund will fluctuate in response to factors that may affect the single issuer, industry, or sector of the economy or may affect the market as a whole. Bonds are subject to a variety of risks including interest rate, credit, and inflation risk. The Funds’ environmental criteria limit the investments available to the Funds compared to mutual funds that do not use environmental criteria.

The S&P 500^® Index⁵ and the S&P Supercomposite 1500 Index (the S&P 1500 Index) are unmanaged indexes of 500 and 1500 stocks, respectively. The Custom Balanced Index is comprised of a 60% weighting in the S&P 1500 Index and a 40% weighting in the BofA Merrill Lynch 1-10 Year US Corporate & Government Index (the BofA Merrill Lynch Index). The BofA Merrill Lynch Index tracks the performance of U.S. dollar-denominated investment grade government and corporate public debt issued in the U.S. domestic bond market with at least 1 year and less than 10 years remaining maturity, including U.S. Treasury, U.S. Agency, foreign government, supranational and corporate securities. Similar to the Balanced Fund, the performance of the S&P 500^® Index, the S&P 1500 Index, the Custom Balanced Index and the BofA Merrill Lynch Index reflect reinvestment of dividends and distributions. Unlike the Fund, however, the performance of the S&P 500^® Index, the S&P 1500 Index, the Custom Balanced Index and the BofA Merrill Lynch Index does not include management and other operating expenses. It is not possible to invest directly in an index.

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MANAGEMENT’S DISCUSSION OF FUND PERFORMANCE

GREEN CENTURY EQUITY FUND

Investment Objective    The Green Century Equity Fund (the Equity Fund or the Fund) seeks to achieve long-term total return that matches the performance of an index comprised of the stocks of companies selected based on environmental, social and governance criteria.

Portfolio Orientation    The Fund seeks to achieve its objective by investing in the stocks which make up the MSCI KLD 400 Social ex Fossil Fuels Index⁶ (the KLD400 ex Fossil Fuels Index or the Index), a custom index calculated by MSCI, Inc. The KLD400 ex Fossil Fuels Index is comprised of the common stocks of the approximately 400 companies in the MSCI KLD 400 Social Index (the KLD400 Index), minus the stocks of the companies that explore for, extract, produce, manufacture, or refine coal, oil or gas that are included in the KLD400 Index. The Index also does not include companies that produce or transmit electricity derived from fossil fuels, transmit natural gas, or own carbon reserves.

The KLD400 Index, formerly named the Domini 400 Social Index, is the longest-running socially responsible index. Like other index funds, the Equity Fund is not actively managed in the traditional investment sense, but rather seeks to be nearly fully invested at all times in a broad and diverse portfolio of stocks which meet certain environmental, social and governance (ESG) criteria. The Equity Fund, like many other mutual funds invested primarily in stocks, carries the risk of investing in the stock market. The large companies in which the Equity Fund is invested may perform worse than the stock market as a whole. The Fund’s environmental criteria limit the investments available to the Fund compared to mutual funds that do not use environmental criteria.

The Fund invests in the stocks of companies selected for inclusion in the Index based on a thorough review of environmental, social, and governance factors and includes those companies believed to have the best overall sustainability records. Green Century believes that certain industries impose unique and

GREEN CENTURY EQUITY FUND

INVESTMENT BY INDUSTRY (unaudited)

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onerous risks and/or costs on society. Companies involved in these industries are evaluated based on their level of involvement as well as the impact of that involvement on society. Therefore, companies that derive significant revenues from the manufacture of tobacco products, alcoholic beverages, genetically modified organisms (GMOs), or the operation of gambling enterprises; or have a significant direct ownership share in, operate or design nuclear power plants are not eligible for the Index. Major military contractors and firearms manufacturers are also ineligible. The Index excludes all companies that explore for, extract, produce, manufacture, or refine coal, oil or gas. The Index also does not include companies that produce or transmit electricity derived from fossil fuels, transmit natural gas, or own carbon reserves.

Investment Strategy and Performance    Green Century believes that companies that minimize their negative social and environmental impact and follow governance standards could enjoy competitive advantages and be less likely to incur certain legal liabilities that may be assessed when a product or service is determined to be harmful. Green Century also believes that such investments may, over the long term, provide investors with a return that is competitive with enterprises that do not exhibit such social and environmental awareness.

The Equity Fund’s total return for the latest quarter ended July 31, 2020 was 12.86% for the individual share class and 12.91% for the institutional share class, closely tracking the S&P 500^® Index, which returned 12.87% for the same period. Additional results for various time periods are below:*

* The performance data quoted represents past performance and is not a guarantee of future results. Investment return and principal value of an investment will fluctuate so that an investor’s shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance information quoted. To obtain Fund prices and performance information as of the most recent month-end, call 1-800-93-GREEN/1-800-934-7336. Performance includes the reinvestment of income dividends and capital gains distributions. Performance shown does not reflect the deduction of taxes that a shareholder might pay on Fund distributions or the redemption of Fund shares. A redemption fee of 2.00% may be imposed on redemptions or exchanges of shares you have owned for 60 days or less. Please see the prospectus for more information.

As of April 1, 2014, the Equity Fund invests in the common stocks which make up the MSCI KLD 400 Social ex Fossil Fuels Index; prior to April 1, 2014, the Fund invested in the common stocks which made up the MSCI KLD 400 Social Index. Institutional shares were offered as of April 30, 2018. The Institutional Share Class performance for periods prior to April 30, 2018 reflects the performance of the Fund’s Individual Investor Class.

For the year ended July 31, 2020, the Equity Fund institutional and investor share classes returned 14.28% and 13.95%, respectively, outperforming the S&P 500^® Index which returned 11.96%. As the MSCI KLD 400 Social ex Fossil Fuels Index does not include all of the stocks in the S&P 500^® Index and includes some stocks not included in the S&P 500 Index, the performance of the Fund can be expected to differ from the performance of the broader benchmark.

The performance of the Fund, relative to the MSCI Index, was boosted by the positive impact of stock selection in the Utilities and Materials sectors and by not holding securities in the Energy sector. The relative performance of the Fund was negatively impacted by stock selection in the Information Technology and Consumer Discretionary sectors.

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The strongest performing sectors in the Equity Fund were Information Technology, Utilities and Health Care which returned 27.87%, 22.09% and 21.76%, respectively. The worst performing sectors were Real Estate and Industrials, which returned 3.71% and 5.80%, respectively, for the year. Within the S&P 500

Index, Information Technology, Consumer Discretionary and Health Care were the strongest performing sectors, gaining 38.91%, 21.47%, and 18.75%, respectively. The worst performing sectors were Energy and Financials, which returned –38.26% and –12.81%, respectively, for the year.

Despite a sharp decline of more than 30% in the first quarter of 2020, the S&P 500 Index was up nearly 12% in the year—July was nearing all-time highs reached previously in February. The increased volatility stemmed from investor sentiment around the global response to the spreading pandemic. A swift response on interest rate policy and stimulus by the Federal Reserve helped stem the volatility, with a drastic rate cut to zero and an unprecedented stimulus package announced after a surprise meeting in March. Energy was the worst-performing sector in the index for the year, as crude oil prices dipped to negative prices on the front month contract in April, but has recovered since settling in around $40 per barrel in July. All other sectors fluctuated with the market, but one category, Information Technology, outpaced all others and held up the best throughout the volatility and subsequent recovery.

The S&P 500^® Index is an unmanaged index of 500 stocks. Similar to the Equity Fund, the S&P 500^® Index’s performance reflects reinvestment of dividends and distributions. Unlike the Fund, however, the S&P 500^® Index’s performance does not include management and other operating expenses. It is not possible to invest directly in an index.

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MANAGEMENT’S DISCUSSION OF FUND PERFORMANCE

GREEN CENTURY MSCI INTERNATIONAL INDEX FUND

Investment Objective    The Green Century MSCI International Index Fund (the International Fund or the Fund) seeks to achieve long-term total return that matches the performance of an index comprised of the stocks of foreign companies selected based on environmental, social and governance criteria.

Portfolio Orientation    The Fund seeks to achieve its objective by investing in the stocks included in the MSCI World ex USA SRI ex Fossil Fuels Index⁷ (the Index), a custom index calculated by MSCI, Inc. The Index is comprised of the common stocks of the approximately 240 companies in the MSCI World ex USA SRI Index,⁸ minus the stocks of the companies that explore for, extract, process, refine or distribute coal, oil or gas. The Index also does not include companies that produce or transmit electricity derived from fossil fuels, transmit natural gas, or own carbon reserves.

The International Fund is the only responsible, diversified fossil fuel free international index fund available in the U.S. The Fund is also broadly diversified and responsibly screened. Like other index funds, the International Fund is not actively managed in the traditional investment sense, but rather seeks to be nearly fully invested at all times in a broad and diverse portfolio of stocks which meet certain environmental, social and governance (ESG) criteria.

The Fund invests in the stocks of companies selected for inclusion in the Index based on a thorough review of environmental, social, and governance factors and includes those companies believed to have the best overall sustainability records. Green Century believes that certain industries impose unique and onerous risks and/or costs on society. Companies involved in these industries are evaluated based on their level of involvement as well as the impact of that involvement on society. Therefore, companies that

GREEN CENTURY MSCI INTERNATIONAL INDEX FUND

INVESTMENT BY COUNTRY (unaudited)

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derive significant revenues from the manufacture of tobacco products, alcoholic beverages, genetically modified organisms (GMOs), or the operation of gambling enterprises; or have a significant direct ownership share in, operate or design nuclear power plants are not eligible for the Index. Major military contractors and firearms manufacturers are also ineligible. The Index excludes all companies that explore for, extract, produce, manufacture, or refine coal, oil or gas. The Index also does not include companies that produce or transmit electricity derived from fossil fuels, transmit natural gas, or own carbon reserves.

Investment Strategy and Performance    Green Century believes that companies that minimize their negative social and environmental impact and follow governance standards could enjoy competitive advantages and be less likely to incur certain legal liabilities that may be assessed when a product or service is determined to be harmful. Green Century also believes that such investments may, over the long term, provide investors with a return that is competitive with enterprises that do not exhibit such social and environmental awareness.

International markets have continued to perform well recently; both share classes of the International Fund outperformed its benchmark for the latest quarter ended July 31, 2020. The Fund’s total return was 11.35% for the individual share class and 11.46% for the institutional share class for this period, while the MSCI World ex USA Index returned 10.69% for the same period. Additional results for various time periods are below:*

* The performance data quoted represents past performance and is not a guarantee of future results. Investment return and principal value of an investment will fluctuate so that an investor’s shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance information quoted. To obtain Fund prices and performance information as of the most recent month-end, call 1-800-93-GREEN/1-800-934-7336. Performance includes the reinvestment of income dividends and capital gains distributions. Performance shown does not reflect the deduction of taxes that a shareholder might pay on Fund distributions or the redemption of Fund shares. A redemption fee of 2.00% may be imposed on redemptions or exchanges of shares you have owned for 60 days or less. Please see the prospectus for more information.

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For the one year period ended July 31, 2020, the institutional and investor share classes of the Green Century MSCI International Index Fund, which closely tracks the MSCI World ex USA SRI ex Fossil Fuels Index, returned 6.51% and 6.28%, respectively, while the MSCI World ex USA Index (Index), returned

–1.72% during the same period. The difference in performance of the International Fund relative to the Index was largely due to differences in sector allocation and stock selection criteria between the International Fund and the Index.

The strongest performing sectors in the International Fund were Information Technology, Health Care and Utilities, which returned 39.75%, 34.76% and 9.63%, respectively. The worst performing sectors were Real Estate and Financials, which returned –18.01% and –10.84%, respectively, for the year. Within the MSCI World ex USA Index, Information Technology, Health Care and Utilities were the strongest performing sectors, gaining 25.68%, 21.25%, and 11.54%, respectively. The worst performing sectors were Energy and Real Estate, which returned –33.57% and –17.16%, respectively, for the year.

International equities were down almost 2% for the year ended July 31, 2020. Countries around the world were plagued by the rise of a global pandemic that spread throughout the world beginning in late 2019 and early 2020. The pandemic forced a global economic shutdown as a response to its rapid infection rate in order to prevent additional spreading.

The MSCI World ex USA Index is a custom index calculated by MSCI Inc. The MSCI World ex USA Index includes large and mid-cap stocks across 22 of 23 Developed Markets (DM) countries and excludes the United States. With 1,023 constituents, the index covers approximately 85% of the free float-adjusted market capitalization in each country. The MSCI World ex USA Index is a free float-adjusted market capitalization index. Unlike the Fund, the MSCI World ex USA Index’s performance does not include management and other operating expenses. It is not possible to invest directly in an index.

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The U.S. Federal Reserve took a proactive stance against the virus, cutting interest rates to zero and announcing unprecedented stimulus in a surprise meeting in March. This development, combined with other nations utilizing similar economic tools, contributed to a swift stock market recovery off of multi-year lows reached in the first quarter of 2020. Technology stocks led other sectors on the year as they performed well during the volatility as well as leading the subsequent recovery.

The International Fund, like many other mutual funds invested primarily in stocks, carries the risk of investing in the stock market. The large companies in which the International Fund is invested may perform worse than the stock market as a whole. The developed market ex-U.S. equities in which the International Fund is invested may also perform worse than the stock market as a whole. Foreign securities are subject to additional risks such as currency fluctuations, regional economic and political conditions, differences in accounting methods, and other unique risks compared to investing in securities of U.S. issuers. The International Fund will not shift concentration from one industry to another or from stocks to bonds or cash, in order to defend against a falling stock market. The Fund’s environmental criteria limit the investments available to the Fund compared to mutual funds that do not use environmental criteria.

¹ As of July 31, 2020, the following companies comprised the listed percentages of each of the Green Century Funds:

Portfolio composition will change due to ongoing management of the Funds. Please refer to the Green Century Funds website for current information regarding the Funds’ portfolio holdings. Note that some of the holdings discussed above may not have been held by any Fund during the fiscal year ended July 31, 2020, or may have been held by a Fund for a portion of the fiscal year, or may have been held by a Fund for the entire fiscal year. These holdings are subject to risk as described in the Funds’ prospectus. References to specific investments should not be construed as a recommendation of the securities by the Funds, their administrator, or their distributor.

² The Custom Balanced Index is comprised of a 60% weighting in the S&P 1500 Index and a 40% weighting in the BofA Merrill Lynch 1-10 Year US Corporate & Government Index (the BofA Merrill Lynch Index). It is not possible to invest directly in the Custom Balanced Index.

³ The S&P Supercomposite 1500 Index is an unmanaged broad-based capitalization-weighted index comprising 1500 stocks of large-cap, mid-cap, and small-cap U.S. companies. It is not possible to invest directly in the S&P Supercomposite 1500 Index.

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⁴ The BofA Merrill Lynch Index tracks the performance of U.S. dollar-denominated investment grade government and corporate public debt issued in the U.S. domestic bond market with at least 1 year and less than 10 years remaining maturity, including U.S. treasury, U.S. agency, foreign government, supranational and corporate securities. It is not possible to invest directly in the BofA Merrill Lynch Index.

⁵ The S&P 500^® Index is an unmanaged index of 500 selected common stocks, most of which are listed on the New York Stock Exchange. The S&P 500^® Index is heavily weighted toward stocks with large market capitalization and represents approximately two-thirds of the total market value of all domestic stocks. It is not possible to invest directly in the S&P 500^® Index.

⁶ The MSCI KLD 400 Social ex Fossil Fuels Index (the KLD400 ex Fossil Fuels Index) is a custom index calculated by MSCI Inc. The KLD400 ex Fossil Fuels Index is comprised of the common stocks of the approximately 400 companies in the MSCI KLD 400 Social Index (the KLD400 Index), minus the stocks of the companies that explore for, extract, produce, manufacture, or refine coal, oil or gas or produce or transmit electricity derived from fossil fuels or transmit natural gas or have carbon reserves that are included in the KLD400 Index. The KLD400 Index is a free float-adjusted market capitalization index designed to provide exposure to U.S. companies that have positive ESG characteristics and consists of approximately 400 companies selected from the MSCI USA Investable Market Index. It is not possible to invest directly in an index.

⁷ The World ex USA SRI ex Fossil Fuels Index is a custom index calculated by MSCI Inc. The World ex USA SRI ex Fossil Fuels Index is comprised of the common stocks of the companies in the MSCI World ex USA SRI Index (the World ex USA SRI Index), minus the stocks of the companies that explore for, extract, produce, manufacture or refine coal, oil or gas or produce or transmit electricity derived from fossil fuels or transmit natural gas or have carbon reserves that are included in the World ex USA SRI (Socially Responsible Investment) Index. The World ex USA SRI Index includes large and mid-cap stocks from approximately 22 Developed Markets countries (excluding the U.S.). The World ex USA SRI Index is a capitalization weighted index that provides exposure to companies with what MSCI calculates to have outstanding ESG ratings and excludes companies whose products have negative social or environmental impacts. It is not possible to invest directly in an index.

⁸ The MSCI World ex USA Index is a custom index calculated by MSCI Inc. The MSCI World ex USA Index includes large and mid-cap stocks across 22 of 23 Developed Markets countries and excludes the United States. With 1,023 constituents, the index covers approximately 85% of the free float-adjusted market capitalization in each country. The MSCI World ex USA Index is a free float-adjusted market capitalization index. It is not possible to invest directly in the MSCI World ex USA Index.

Stocks will fluctuate in response to factors that may affect a single company, industry, sector, country, region or the market as a whole and may perform worse than the market. Foreign securities are subject to additional risks such as currency fluctuations, regional economic and political conditions, differences in accounting methods, and other unique risks compared to investing in securities of U.S. issuers. Bonds are subject to a variety of risks including interest rate, credit, and inflation risk. A sustainable investment strategy which incorporates environmental, social and governance criteria may result in lower or higher returns than an investment strategy that does not include such criteria.

This material must be preceded or accompanied by a current prospectus.

Distributor: UMB Distribution Services, LLC 9/20

Neither the Green Century Equity Fund nor the Green Century MSCI International Index Fund (each a “Fund” and together the “Funds”) is sponsored, endorsed, or promoted by MSCI, its affiliates, information providers or any other third party involved in, or related to, compiling, computing or creating the MSCI indices (the “MSCI Parties”), and the MSCI Parties bear no liability with respect to a Fund or any index on which a Fund is based. The MSCI Parties are not sponsors of either of the Funds and are not affiliated with the Funds in any way. The Statement of Additional Information contains a more detailed description of the limited relationship the MSCI Parties have with Green Century Capital Management and the Funds.

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GREEN CENTURY FUNDS EXPENSE EXAMPLE

For the six months ended July 31, 2020 (unaudited)

As a shareholder of the Green Century Funds (the “Funds”), you incur two types of costs: (1) transaction costs, including redemption fees on certain redemptions; and (2) ongoing costs, including management fees and other Fund expenses. This example is intended to help you understand your ongoing costs (in dollars) of investing in the Funds and to compare these costs with the ongoing costs of investing in other mutual funds.

The example is based on an investment of $1,000 invested at the beginning of the period and held for the entire period from February 1, 2020 to July 31, 2020 (the “period”).

Actual Expenses    The first line of the table below provides information about actual account values and actual expenses. You may use the information in this line, together with the amount you invested, to estimate the expenses you paid over the period. Simply divide your account value by $1,000 (for example, an $8,600 account value divided by $1,000 equals 8.6), then multiply the result by the number in the first line under the heading entitled “Expenses Paid During the Period” to estimate the expenses you paid on your account during the period.

Hypothetical Example for Comparison Purposes    The second line of the table below provides information about hypothetical account values and hypothetical expenses based on the Funds’ actual expense ratios and an assumed rate of return of 5% per year before expenses, which is not the actual return of either of the Funds. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period. You may use this information to compare the ongoing costs of investing in the Funds and other funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of other funds.

Please note that the expenses shown in the table are meant to highlight your ongoing costs only and do not reflect any transactional costs, such as redemption fees on shares held for 60 days or less. Therefore, the second line of the table is useful in comparing the ongoing costs only, and will not help you determine the relative total costs of owning different funds. In addition, if these transactional costs were included, your costs could have been higher.

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¹ Expenses are equal to the Funds’ annualized expense ratios (1.47% for the Balanced Fund, 1.25% for the Equity Fund Individual Investor Class, 0.95% for the Equity Fund Institutional Class, 1.28% for the MSCI International Index Fund Individual Investor Class and 0.98% for the MSCI International Index Fund Institutional Class), multiplied by the average account value over the period, multiplied by 182/366 (to reflect the one-half year period).

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See Notes to Financial Statements

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