Filed Pursuant to Rule 497(k)
1933 Act File No. 002-93131
1940 Act No. 811-04044

Summary Prospectus

May 1, 2019

Parnassus Fund^SM

Investor Shares: PARNX | Institutional Shares: PFPRX

Before you invest, you may want to review the Fund’s prospectus, which contains more information about the Fund and its risks. You can find the Fund’s prospectus, reports to shareholders, and other information about the Fund, including the statement of additional information, online at www.parnassus.com. You can also get this information at no cost by calling (800) 999-3505 or by sending an e-mail request to shareholder@parnassus.com. The Fund’s prospectus and statement of additional information, both dated May 1, 2019, as may be supplemented from time to time, are incorporated by reference into this summary prospectus.

Beginning on January 1, 2021, as permitted by regulations adopted by the SEC, paper copies of the Funds’ shareholder reports will no longer be sent by mail, unless you specifically request paper copies of the reports from the Funds or from your financial intermediary, such as a broker-dealer or bank. Instead, the reports will be made available on the Funds’ website (www.parnassus.com), and you will be notified by mail each time a report is posted and provided with a website link to access the report.

If you already elected to receive shareholder reports electronically, you will not be affected by this change and you need not take any action. You may elect to receive shareholder reports and other communications from the Funds by contacting your financial intermediary (such as a broker-dealer or bank) or, if you are a direct investor, by calling 800-999-3505 or by sending an email request to shareholder@parnassus.com.

You may elect to receive all future reports in paper copies free of charge. If you invest through a financial intermediary, you can contact your financial intermediary to request that you continue to receive paper copies of your shareholder reports. If you invest directly with the Funds, you can call 800-999-3505 or send an email request to shareholder@parnassus.com to let the Funds know you wish to continue receiving paper copies of your shareholder reports. Your election to receive paper copies of reports will apply to all funds held in your account if you invest through your financial intermediary.

Parnassus Fund

Investment Objective

The Parnassus Fund has the overall investment objective of capital appreciation.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the Parnassus Fund.

Parnassus Fund

Annual Fund Operating Expenses (%)
(expenses that you pay each year as a percentage of the value of your investment)
	Investor Shares		Institutional Shares
Management Fees		0.62		0.62
Distribution (12b-1) Fees		None		None
Other Expenses		0.23		0.07
Service Fees		0.13		None
All remaining other expenses		0.10		0.07
Total Annual Fund Operating Expenses		0.85		0.69

For additional information about the Parnassus Fund’s expenses, please see “Financial Highlights” in the prospectus.

Example

This example is intended to help you compare the cost of investing in the Parnassus Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment has a 5% return each year, and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, under these assumptions, your costs would be:

	1 Year		3 Years		5 Years		10 Years
Investor Shares		$87		$271		$471		$1,049
Institutional Shares		$70		$221		$384		$859

Portfolio Turnover

The Parnassus Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 47.3% of the average value of its portfolio.

Principal Investment Strategies

The Parnassus Fund invests in undervalued stocks. This Fund follows a “contrarian” strategy of seeking to invest in stocks that are currently out of favor with the financial community and are therefore, in the opinion of the Fund’s investment adviser (Adviser), deeply undervalued. The Adviser expects that if these undervalued companies are financially strong and have good prospects for the future, they will come back into favor and increase in market value. The Parnassus Fund is a “multi-cap” fund in that it can invest in companies of any size, from larger, well-established companies to smaller companies. The Fund invests mainly in domestic stocks of companies that are financially sound and have good prospects for the future, and to a lesser extent may also invest in foreign securities of similar companies. The Fund may purchase foreign securities directly on foreign markets. The Fund is fossil-fuel free, as it does not invest in companies that derive significant revenues from the extraction, exploration, production or refining of fossil fuels; the Fund may invest in companies that use fossil fuel-based energy to power their operations or for other purposes. To determine a company’s prospects, the Adviser reviews the company’s income statement, cash flow statement and balance sheet, and analyzes the company’s sustainable strategic advantage and management team. Upon initial investment, a company’s stock must be trading below its intrinsic value, which means that the Adviser seeks to purchase stock trading at a discount to the Adviser’s assessment of the company’s estimated value. The Adviser also

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takes environmental, social and governance (“ESG”) factors into account in making investment decisions. The Fund will sell a security if the Adviser believes a company’s fundamentals will deteriorate, if it believes a company’s stock has little potential for appreciation or if the company no longer meets the Adviser’s ESG criteria.

Principal Risks

All investments involve risk, and investing in the Parnassus Fund is no exception. You could lose money investing in the Fund. The likelihood of loss may be greater if you invest for a shorter period of time. The Fund is intended for investors who can accept that there will be fluctuations in value. Investments in the Fund are not deposits, endorsements or guarantees of any bank and are not insured by the Federal Deposit Insurance Corporation or any other government agency. The Fund’s principal risks include the following:

∎ Stock Market Risk. The Fund invests in common stocks, whose prices fluctuate in response to the fortunes of individual companies and in response to general market and economic conditions both in the U.S. and abroad. In the past decade financial markets throughout the world have experienced increased volatility, decreased liquidity and heightened uncertainty. The Fund’s holdings can vary significantly from broad stock market indices.

∎ Large-Capitalization Company Risk. Large-capitalization companies may be unable to respond quickly to new competitive challenges and also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

∎ Small- and Mid-Capitalization Company Risk. This is a “multi-cap” fund. In addition to large-capitalization companies, the Fund may invest in small- and/or mid-capitalization companies, which can be particularly sensitive to changing economic conditions since they do not have the financial resources or the well-established businesses of large-capitalization companies. Relative to the stocks of large-capitalization companies, the stocks of small- and mid-capitalization companies are often thinly traded, and purchases and sales may result in higher transaction costs. Also, small-capitalization companies tend to perform poorly during times of economic stress.

∎ Management Risk. The Adviser may be wrong in its assessment of a company’s value and/or the stocks the Fund holds may not reach what the Adviser believes are their full values. From time to time, “value” investing falls out of favor with investors, and during those periods the Fund’s relative performance may suffer.

∎ Foreign Securities Risk. The Fund may invest up to 20% of its assets in foreign securities. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market or economic developments and can perform differently from the U.S. market. Policy and legislative changes in foreign countries and other events affecting global markets, such as the United Kingdom’s expected exit from the European Union (or Brexit), may contribute to decreased liquidity and increased volatility in the financial markets. Further, foreign companies may be subject to significantly higher levels of taxation than U.S. companies, including potentially confiscatory levels of taxation, thereby reducing the earnings potential of such foreign companies. Substantial withholding taxes may also apply to distributions from foreign companies.

Performance Information

The bar chart and table that follow contain information that allows you to evaluate the Parnassus Fund’s performance using several measures, such as yearly changes in performance, best and worst quarterly returns, and average annual total returns before and after taxes compared to a broad measure of market performance. The bar chart shows the performance of the Fund’s Investor Shares, and the performance of the Fund’s Institutional Shares will differ from those shown to the extent that the classes of shares do not have the same expenses or inception date. How the Fund performed in the past (before and after taxes) is not necessarily an indication of how it will perform in the future. Updated performance information is available on the Fund’s website, www.parnassus.com, or by calling toll-free at (800) 999-3505.

During the ten-year period shown in the bar chart, the highest return for a quarter was 19.9% (quarter ended September 30, 2009), and the lowest return for a quarter was a loss of 19.4% (quarter ended September 30, 2011).

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Following is a table comparing the performance of the Parnassus Fund’s two share classes with that of the S&P 500^® Index (see “Index Descriptions” in the prospectus) and the Lipper Multi-Cap Core Funds Average. Figures are average annual returns for the one-, five- and ten-year periods ended December 31, 2018. The table is intended to demonstrate the risk of investing in the Parnassus Fund by showing how the Fund’s average annual total returns, before and after taxes, compare with a broad measure of market performance, the S&P 500^® Index, and a group of similar mutual funds, the Lipper Multi-Cap Core Funds Average, and also how the Fund’s performance varies from year to year.

Parnassus Fund

Average Annual Total Returns (%)
(all periods ended December 31, 2018)
	One Year		Five Years		Ten Years
Investor Shares
Return before Taxes		-9.73		6.45		14.26
Return after Taxes on Distributions		-11.24		4.29		12.34
Return after Taxes on Distributions and Sale of Fund Shares		-4.56		4.92		11.82
Institutional Shares
Return before Taxes		-9.57		6.56		14.32
S&P 500® Index (reflects no deduction for fees, expenses or taxes)		-4.38		8.49		13.12
Lipper Multi-Cap Core Funds Average		-7.88		5.52		11.61

The after-tax returns are calculated using the historical highest individual stated federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s individual tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of Fund shares. After-tax returns are shown for Investor Shares only. After-tax returns for Institutional Shares will vary.

Parnassus Fund—Institutional Shares were incepted on April 30, 2015. Performance shown prior to the inception of the Institutional Shares reflects the performance of the Parnassus Fund—Investor Shares and includes expenses that are not applicable to and are higher than those of the Institutional Shares.

The Adviser

Parnassus Investments is the investment adviser to the Parnassus Fund. For more information on the Adviser, please see “Management of the Funds” in the prospectus and “The Adviser” in the statement of additional information.

Portfolio Managers

Ian E. Sexsmith is a Co-Portfolio Manager of the Parnassus Fund and has served as a portfolio manager since 2013. He is equally responsible for the day-to-day management of the Parnassus Fund with the other Portfolio Manager of the Fund.

Robert J. Klaber is a Co-Portfolio Manager of the Parnassus Fund and has served as a portfolio manager since 2016. He is equally responsible for the day-to-day management of the Parnassus Fund with the other Portfolio Manager of the Fund.

For more information, please see “Management of the Funds” in the prospectus and “Portfolio Managers” in the statement of additional information.

For important information about the purchase and sale of Fund shares, tax information and payments to financial intermediaries, please turn to “Additional Summary Information” on page 17 of the prospectus.

Purchase and Sale of Fund Shares

The Fund offers two classes of shares: Investor Shares and Institutional Shares. For Investor Shares, the minimum initial purchase is $2,000, with a minimum of $500 for certain custodial accounts and IRAs. The minimum investment in an automatic investment plan is $50. The minimum subsequent investment is $50. For Institutional Shares, the minimum initial purchase is $100,000.

You may redeem and purchase shares of the Fund each day the New York Stock Exchange is open. You may redeem or purchase Fund shares online through our website at www.parnassus.com, by mail (Parnassus Funds, 1 Market Street, Suite 1600, San Francisco, CA 94105), or by telephone at 800-999-3505. Investors who wish to redeem or purchase shares through a broker-dealer or other financial intermediary should contact the intermediary regarding the hours during which orders may be placed.

For additional information, please see “Investing with Parnassus Funds” on page 24 of the prospectus.

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Tax Information

The Fund’s distributions will be taxed as ordinary income or capital gains, unless you are investing through a tax-deferred arrangement, such as a 401(k) plan or an individual retirement account in which case such distribution may be taxable at a later date.

Financial Intermediary Compensation

If you purchase the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies may pay the intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the brokerdealer or other intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary’s website for more information.

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Investment Adviser

Parnassus Investments

1 Market Street, Suite 1600

San Francisco, CA 94105

Independent Registered Public Accounting Firm

Deloitte and Touche LLP

555 Mission Street

San Francisco, CA 94105

Legal Counsel

Foley and Lardner LLP

777 E. Wisconsin Ave.

Milwaukee, WI 53202

Distributor

Parnassus Funds Distributor, LLC

Three Canal Plaza, Suite 100

Portland, ME 04101

You can obtain additional information about each of the Funds in the statement of additional information (SAI) dated May 1, 2019, which has been filed with the Securities and Exchange Commission (SEC) and is incorporated in this prospectus by reference (namely, it legally forms a part of the prospectus). The Funds also publish an annual and a semiannual report and two quarterly reports each year that discuss the Funds’ holdings and how recent market conditions as well as the Funds’ investment strategies affected performance. For a free copy of any of these documents or to ask questions about the Funds, call the Parnassus Funds at (800) 999-3505.

The Funds make available the SAI and the annual and semiannual reports, free of charge, on their Internet website (http://www. parnassus.com). This information may also be reviewed and copied at the Public Reference Room of the SEC in Washington, D.C. or by visiting the SEC’s Internet website at http://www.sec.gov. In addition, copies of this information may be obtained after paying a duplicating fee by emailing the Public Reference Room of the SEC at publicinfo@sec.gov or by writing to: Public Reference Room, Securities and Exchange Commission, Washington, D.C. 20549-1520. You may also call the SEC at (202) 551-8090 for information on the operation of the Public Reference Room.

The Investment Company Act File Number for Parnassus Income Funds is 811-06673. The Investment Company Act File Number for Parnassus Funds is 811-04044.

1 Market Street, Suite 1600, San Francisco, CA 94105_^(800)  999-3505_^www.parnassus.com