UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 4)*

Learning Tree International, Inc.

(Name of Issuer)

Common Stock, $0.0001 par value

(Title of Class of Securities)

522015106

(CUSIP Number)

Mill Road Capital, L.P.

Attn: Thomas E. Lynch

382 Greenwich Avenue

Suite One

Greenwich, CT 06830

203-987-3500

With a copy to:

Peter M. Rosenblum, Esq.

Foley Hoag LLP

155 Seaport Blvd.

Boston, MA 02210

617-832-1151

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

March 8, 2013

(Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.  ¨

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are sent.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

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This Amendment No. 4 to the joint statement on Schedule 13D with respect to the common stock, $0.0001 par value, of Learning Tree International, Inc., a Delaware corporation, filed by Mill Road Capital, L.P., a Delaware limited partnership (the “Mill Road Fund”), Mill Road Capital GP LLC, a Delaware limited liability company (the “Mill Road Fund GP”), Thomas E. Lynch and Scott P. Scharfman (collectively, the “Mill Road Reporting Persons”) on October 29, 2012, as amended by the Amendment No. 1 on Schedule 13D filed by the Mill Road Reporting Persons on November 13, 2012, as amended and restated by Amendment No. 2 on Schedule 13D filed by the undersigned on November 19, 2012, and as amended by Amendment No. 3 on Schedule 13D filed by the undersigned on February 5, 2013 (such filing, as so amended and as amended herein, the “Schedule 13D”), amends the Schedule 13D as follows:

‘On March 8, 2013, the Mill Road Fund and the Lane Five Advisor sent the letter attached hereto as Exhibit 9 to the nominating and corporate governance committee of the Issuer’s board of directors. The letter proposes Ms. Rapuano and Stephen Quattrociocchi for the committee’s consideration as nominees for election to the Issuer’s board of directors at the 2013 annual meeting of the Issuer’s stockholders.’

‘The percentages of beneficial ownership reported for the Reporting Persons in this Item 5, and on each Reporting Person’s cover page to this Schedule 13D, are based on a total of 13,217,484 shares of Common Stock issued and outstanding as of January 31, 2013, as reported in the most recent quarterly report of the Issuer on Form 10-Q for the fiscal quarter ended December 28, 2012. All of the share numbers reported below, and on each Reporting Person’s cover page to this Schedule 13D, are as of March 12, 2013, unless otherwise indicated.’

‘No Reporting Person or other Pleiades Entity effected any transaction in the shares of Common Stock from February 6, 2013 (the day after the filing of Amendment No. 3 to this Schedule 13D) to March 12, 2013.’

Signature

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Exhibit 9

March 8, 2013

VIA FEDEX

Nominating and Corporate Governance Committee

Learning Tree International, Inc.

1805 Library Street

Reston, Virginia 20190

Attn: Charles R. Waldron, Secretary

Gentlemen:

Pursuant to the statement contained in Item 8.01 of the Company’s Current Report on Form 8-K dated February 27, 2013 (the “Form 8-K”), Mill Road Capital, L.P., a Delaware limited partnership (“Mill Road”), and Lane Five Capital Management LP, a Delaware limited partnership (“Lane Five” and, together with Mill Road, the “Stockholders”), hereby submit for your consideration two candidates for nomination for election to the Board of Directors of the Company (the “Board”) at the 2013 Annual Meeting of Stockholders of the Company, or any other meeting of stockholders held in lieu thereof, and any adjournments, postponements, reschedulings or continuations thereof (the “Annual Meeting”). This letter, including the attachments hereto, is referred to as the “Proposal.” The persons the Stockholders propose for nomination for election to the Board as Class II directors at the Annual Meeting are Lisa O’Dell Rapuano and Stephen Quattrociocchi (each a “Candidate” and collectively, the “Candidates”). Attached hereto as Exhibits A and B, respectively, are the current curriculum vitaes for Ms. Rapuano and Mr. Quattrociocchi.

Ms. Rapuano is the Founder, Chief Executive Officer, and Portfolio Manager of Lane Five Capital Management, a fundamental, long-term oriented investment fund and a significant, long-term stockholder of the Company. Ms. Rapuano is also a Director and member of both the Nominating and Compensation Committees of Ambassadors Group, Inc., a publicly-listed, educational company that organizes and promotes travel programs for students and professionals worldwide. Ms. Rapuano’s depth of experience in evaluating companies from a financial, operational, capital allocation, and strategic perspective and her experience as a public company director will enable her to provide effective oversight of the Company. Additionally, her status as manager of Lane Five gives her particular insight as a representative of the stockholders.

Mr. Quattrociocchi has spent his career in the education industry. Most recently, Mr. Quattrociocchi was President and COO of the 30,000 student Online Division of Corinthian Colleges Inc., a post-secondary education company. Prior to his five years at Corinthian he spent 20 years at The Princeton Review, Inc., which provides in-person, online, and print education products and services for the high school (SAT) and post-secondary (GMAT, LSAT, MCAT, etc.) markets. He served as Executive Vice President and General Manager of the Test Preparation Services Division. Mr. Quattrociocchi has extensive operational experience including expertise in designing and delivering effective instruction, customer acquisition, classroom loading, as well as online learning. His combined experience at Corinthian Colleges and The Princeton Review will enable him to provide strategic guidance and effective oversight to the Company.

In furtherance of the Proposal, the undersigned hereby set forth the following:

The Stockholders expect that each Candidate will furnish such other information as the Company may reasonably require to determine the eligibility and suitability of such Candidate to serve as a director of the Company (without, in each case, conceding the validity of any such requirement or request for additional information). If either of the Candidates is selected by the Company as a nominee for election as a director, upon request of the Board, that Candidate will furnish to the Secretary of the Company such information regarding himself or herself as is required to be set forth in any proxy materials to be furnished to stockholders in accordance with the relevant regulations promulgated by the SEC.

Representatives of the Stockholders would be pleased to meet with the members of the Nominating and Corporate Governance Committee or the full Board, either in person or telephonically, to discuss the proposed nomination of the Candidates for election to the Board. Additionally, the Stockholders would be pleased to facilitate meetings between the Board and either or both of the Candidates for purposes of determining their suitability as nominees for election to the Board.

In the event that the Company does not nominate the Candidates for election to the Board at the Annual Meeting, the Stockholders reserve the right to attend the Annual Meeting in person or by proxy to, among other things, directly nominate the Candidates, or any other suitable person, for election as directors. The Stockholders also reserve the right to give further notice of additional business or nominations to be conducted or made at the Annual Meeting or other meeting of the Company’s stockholders, or to revise the proposed nominations described herein.

We look forward to your prompt reply. Please address any correspondence or questions to Mill Road Capital, L.P., Attention: Justin Jacobs, telephone (203) 987-3505, facsimile (203) 621-3280 (with a copy to Mill Road’s counsel, Foley Hoag LLP, Seaport West, 155 Seaport Blvd., Boston, MA 02210, Attention: Peter M. Rosenblum, Esq., telephone (617) 832-1151, and Paul Bork, telephone (617) 832-1113, facsimile (617) 832-7000)) and Lane Five Capital Management LP, Attention: Lisa Rapuano, telephone (443) 921-2061, facsimile (443)-921-2098 (with a copy to Lane Five’s counsel, Sadis & Goldberg 551 Fifth Avenue, 21^st Floor, New York, NY 10176. Attention: Dan Viola, telephone 212-573-8038, facsimile (212) 947-3796.)