Harbor Capital Appreciation Fund

Institutional Class HACAX

Administrative Class HRCAX

Investor Class HCAIX

Retirement Class HNACX

Harbor Capital Appreciation Fund

Summary Prospectus – March 1, 2016

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 and other information about the Fund online at harborfunds.com/prospectus. You can also get this information at no cost by calling 800-422-1050 or by sending an e-mail request to funddocuments@harborfunds.com. If you purchase shares of the Fund through a financial intermediary, the prospectus and other information will also be available from your financial intermediary. The current prospectus and statement of additional information, dated March 1, 2015, are incorporated by referenced into this summary prospectus and may be obtained, free of charge, at the website, phone number or e-mail address noted above.

Investment Objective

The Fund seeks long-term growth of capital.

Fees and Expenses of the Fund

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

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

	Institutional Class	Administrative Class	Investor Class	Retirement Class
Management Fees¹	0.60%	0.60%	0.60%	0.60%
Distribution and Service (12b-1) Fees	None	0.25%	0.25%	None
Other Expenses²	0.10%	0.10%	0.22%	0.05%
Total Annual Fund Operating Expenses²	0.70%	0.95%	1.07%	0.65%
Fee Waiver^1,2	0.05%	0.05%	0.05%	0.05%
Total Annual Fund Operating Expenses After Fee Waiver^1,2	0.65%	0.90%	1.02%	0.60%

¹ The Adviser has contractually agreed to reduce the management fee to 0.56% on assets between $5 billion and $10 billion, 0.54% on assets between $10 billion and $20 billion and 0.53% on assets over $20 billion through February 28, 2017. Only the Board of Trustees may modify or terminate this agreement.

² Restated to reflect current fees.

Expense Example

This Example is intended to help you compare the cost of investing in the 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. 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:

	One Year	Three Years	Five Years	Ten Years
Institutional Class	$ 66	$218	$383	$ 862
Administrative Class	$ 92	$297	$519	$1,158
Investor Class	$104	$334	$584	$1,298
Retirement Class	$ 61	$202	$356	$ 802

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover 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. The Fund’s portfolio turnover rate in the most recent fiscal year was 37%.

Principal Investment Strategy

Principal Style Characteristics: Mid to large cap growth stocks

The Fund invests primarily in equity securities, principally common and preferred stocks, of U.S. companies with market capitalizations of at least $1 billion at the time of purchase and that the Subadviser considers to have above average prospects for growth.

The Subadviser uses a bottom-up approach, researching and evaluating individual companies, to manage the Fund’s portfolio. This research includes visits to companies and discussions with company management.

In selecting stocks for the Fund’s portfolio, the Subadviser looks for companies that it believes have the following financial characteristics:

■	Superior absolute and relative earnings growth
■	Superior sales growth, improving sales momentum and high levels of unit growth
■	High or improving profitability
■	Strong balance sheets

In addition, the Subadviser looks for companies that have actually achieved or exceeded expected earnings results and, in the opinion of the Subadviser, are attractively valued relative to their growth prospects.

The Subadviser focuses on stocks of companies that it believes have distinct attributes such as:

■	Strong market position with a defensible franchise
■	Unique marketing competence
■	Strong research and development leading to superior new product flow
■	Capable and disciplined management

The Subadviser prefers companies that are in the early stages of demonstrating the above financial and other characteristics.

The stocks of mid and large cap companies in the Fund’s portfolio are those the Subadviser expects to maintain or achieve above average earnings growth. The Fund may invest up to 20% of its total assets in the securities of foreign issuers, including issuers located or doing business in emerging markets.

Principal Risks

There is no guarantee that the investment objective of the Fund will be achieved. Stocks fluctuate in price and the value of your investment in the Fund may go down. This means that you could lose money on your investment in the Fund or the Fund may not perform as well as other possible investments. Principal risks include:

Summary Prospectus
Harbor Capital Appreciation Fund

Market and Issuer Risk: Securities markets are volatile and can decline significantly in response to adverse market, economic, political, regulatory or other developments, which may lower the value of securities held by the Fund, sometimes rapidly or unpredictably. Additionally, an adverse event, such as an unfavorable earnings report, may depress the value of a particular issuer’s stock.

Growth Style Risk: Over time, a growth oriented investing style may go in and out of favor, which may cause the Fund to underperform other equity funds that use different investing styles.

Selection Risk: The Subadviser’s judgment about the attractiveness, value and potential appreciation of a particular security may be incorrect.

Large Cap Risk: Large cap stocks may fall out of favor relative to small or mid cap stocks, which may cause the Fund to underperform other equity funds that focus on small or mid cap stocks.

Mid Cap Risk: The Fund’s performance may be more volatile because it invests in mid cap stocks. Mid cap companies may have limited product lines, markets and financial resources. They are usually less stable in price and less liquid than those of larger, more established companies. Additionally, mid cap stocks may fall out of favor relative to small or large cap stocks, which may cause the Fund to underperform other equity funds that focus on small or large cap stocks.

Foreign Securities Risk: Because the Fund may invest in securities of foreign issuers, an investment in the Fund is subject to special risks in addition to those of U.S. securities. These risks include heightened political and economic risks, greater volatility, currency fluctuations, higher transaction costs, delayed settlement, possible foreign controls on investment, possible sanctions by governmental bodies of other countries and less stringent investor protection and disclosure standards of foreign markets. Foreign securities are sometimes less liquid and harder to value than securities of U.S. issuers. These risks are more significant for issuers in emerging market countries. Global economies and financial markets are becoming increasingly interconnected, and conditions and events in one country, region or financial market may adversely impact issuers in a different country, region or financial market.

Performance

The following bar chart and table show two aspects of the Fund: volatility and performance. The bar chart shows the volatility — or variability — of the Fund’s annual total returns over time, and shows that Fund performance can change from year to year. The table shows the Fund’s average annual total returns for certain time periods compared with those of the Fund’s benchmark index and other comparative indices, which have investment characteristics similar to those of the Fund. The bar chart and table provide some indication of the risks and potential rewards of investing in the Fund. The Fund’s past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. To obtain updated performance information please visit the Fund’s website at harborfunds.com or call 800-422-1050.

Calendar Year Total Returns for Institutional Class Shares

The Fund’s best and worst calendar quarters during this time period were:

	Total Return	Quarter/Year
Best Quarter	19.08%	Q1 2012
Worst Quarter	-20.75%	Q4 2008

Average Annual Total Returns — As of December 31, 2015

	One Year	Five Years	Ten Years	Since Inception	Inception Date
Harbor Capital Appreciation Fund
Institutional Class Before Taxes	10.99%	14.35%	8.38%	11.45%	12-29-1987
After Taxes on Distributions	9.30%	13.48%	7.94%	N/A
After Taxes on Distributions and Sale of Fund Shares	7.62%	11.50%	6.83%	N/A
Administrative Class Before Taxes	10.72%	14.06%	8.11%	9.73%	11-01-2002
Investor Class Before Taxes	10.58%	13.92%	7.97%	9.56%	11-01-2002
Retirement Class* Before Taxes	10.99%	14.35%	8.38%	11.45%	03-01-2016
Comparative Indices (reflects no deduction for fees, expenses or taxes)
Russell 1000^® Growth	5.67%	13.53%	8.53%	9.91%	12-29-1987
S&P 500	1.38%	12.57%	7.31%	10.27%	12-29-1987

Retirement Class shares commenced operations on March 1, 2016. The performance attributed to the Retirement Class shares prior to that date is that of the Institutional Class shares. Performance prior to March 1, 2016 has not been adjusted to reflect the lower expenses of Retirement Class shares. During this period, Retirement Class shares would have had returns similar to, but somewhat higher than, Institutional Class shares due to the fact that Retirement Class shares represent interests in the same portfolio as Institutional Class shares but are subject to lower expenses.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact

Summary Prospectus
Harbor Capital Appreciation Fund

of state and local taxes. Actual after-tax returns depend on a shareholder’s tax situation and may differ from those shown. The after-tax returns shown are not relevant to tax exempt shareholders or shareholders who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Institutional Class shares only. After-tax returns for the Administrative and Investor Class shares will vary.

Portfolio Management

Investment Adviser

Harbor Capital Advisors, Inc.

Subadviser

Jennison Associates LLC has subadvised the Fund since 1990.

Portfolio Managers

Spiros Segalas
Jennison Associates LLC

Mr. Segalas is a Director, the Chief Investment Officer, President and a founding member of Jennison Associates and has managed the Fund since 1990.

Kathleen A. McCarragher
Jennison Associates LLC

Ms. McCarragher is a Director, Managing Director and the Head of Growth Equity of Jennison Associates and has co-managed the Fund since 2013. She has been involved in portfolio management for the Fund since 1998.

Buying and Selling Fund Shares

Shareholders may purchase or sell (redeem) Fund shares on any business day (normally any day the New York Stock Exchange is open). You may conduct transactions by mail, by telephone or through our website.

By Mail	Harbor Funds P.O. Box 804660 Chicago, IL 60680-4108
By Telephone	800-422-1050
By Visiting Our Website	harborfunds.com

Investors who wish to purchase, exchange or redeem shares held through a financial intermediary should contact the financial intermediary directly.

The minimum initial investment amounts are shown below. The minimums may be reduced or waived in some cases. There are no minimums for subsequent investments.

Type of Account	Institutional Class	Administrative Class¹	Investor Class	Retirement Class²
Regular	$50,000	$50,000	$2,500	None
Individual Retirement Account (IRA)	$50,000	N/A	$1,000	N/A
Custodial (UGMA/UTMA)	$50,000	N/A	$1,000	N/A

¹ Limited only to employer-sponsored retirement or benefit plans and financial intermediaries. There is no minimum investment for employer-sponsored retirement or benefit plans.

² Limited only to employer-sponsored retirement or benefit plans.

Tax Information

Distributions you receive from the Fund are subject to federal income tax and may also be subject to state and local taxes. These distributions will generally be taxed as ordinary income or capital gains, unless you are investing through a tax-deferred retirement account, such as a 401(k) plan or individual retirement account. Investments in tax-deferred accounts may be subject to tax when they are withdrawn.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase the Institutional, Administrative and/or Investor Classes of shares of the Fund through a broker-dealer or other financial intermediary, the Fund and/or its related companies may pay the intermediary for the sale of Fund shares and related services. No compensation may be paid by the Fund and/or its related companies to intermediaries for the sale of Retirement Class shares or related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your sales representative to recommend the Fund over another investment. Ask your sales representative or visit your financial intermediary’s website for more information.

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