UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 10-K/A

ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d)
OF THE SECURITIES EXCHANGE ACT OF 1934

For the Fiscal Year Ended March 31, 2008
Commission File Number: 000-33283

THE ADVISORY BOARD COMPANY

(Exact name of registrant as specified in its charter)

Delaware	52-1468699
(State or other jurisdiction	(I.R.S. Employer
of incorporation or organization)	Identification Number)
2445 M Street, N.W.
Washington, D.C.	20037
(Address of principal executive offices)	(Zip Code)

202-266-5600
(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Name of each exchange on which registered
Common Stock, par value $0.01	The Nasdaq Stock Market LLC
	(Nasdaq Global Select Market)

Securities registered pursuant to Section 12(g) of the Act: Not applicable

     Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes þ No o

     Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes o No þ

     Indicate by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports) and (2) has been subject to such filing requirements for the past 90 days. Yes þ No o

     Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of the registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. o

     Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definition of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act. (Check one):

Large accelerated filer þ Accelerated filer o Non-accelerated filer o
(Do not check if a smaller reporting company) Smaller reporting company o

     Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act). Yes o No þ

     Based upon the closing price of the registrant’s common stock as of September 28, 2007, the aggregate market value of the common stock held by non-affiliates of the registrant was $729,985,145.*

     The number of shares of the registrant’s common stock, par value $0.01 per share, outstanding on May 27, 2008 was 17,316,228.

DOCUMENTS INCORPORATED BY REFERENCE

None.

* Solely for purposes of this calculation, all executive officers and directors of the registrant and all shareholders reporting beneficial ownership of more than 5% of the registrant’s common stock are considered to be affiliates.

Unless the context indicates otherwise, references in this Amendment No. 1 on Form 10-K/A to the “Company,” the “registrant,” “we,” “our” and “us” mean The Advisory Board Company and its subsidiaries.

EXPLANATORY NOTE

     This Amendment No. 1 on Form 10-K/A amends the Company’s Annual Report on Form 10-K for the year ended March 31, 2008 (the “2008 10-K”), filed with the Securities and Exchange Commission on May 30, 2008. This Amendment is being filed solely to correct a filing error in the consent of our independent registered public accounting firm, Ernst & Young LLP, which is filed herewith as Exhibit 23.1.

     In addition, as required by Rule 12b-15 under the Securities Exchange Act of 1934, as amended, new certifications by our principal executive officer and principal financial officer are filed as exhibits to this Form 10-K/A under Item 15 of Part IV hereof.

     This Amendment No. 1 does not reflect events occurring after the original filing date of the 2008 10-K or otherwise modify or update the disclosures set forth in the 2008 10-K, including the financial statements and notes to financial statements set forth in the 2008 10-K.

PART IV

Item 15. Exhibits and Financial Statement Schedules.

Exhibits. The exhibits that are filed with this Amendment No. 1 are set forth in the Index to Exhibits.

SIGNATURES

     Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

	THE ADVISORY BOARD COMPANY
Date: February 27, 2009	By:	/s/ Michael T. Kirshbaum
		Michael T. Kirshbaum
		Chief Financial Officer and Treasurer (Duly Authorized Officer and Principal Financial Officer)

INDEX TO EXHIBITS
to Amendment No. 1 to the Annual Report on Form 10-K/A for the Year Ended March 31, 2008

Exhibit
Number	Description of Exhibit
23.1	Consent of Ernst & Young LLP. Filed herewith.
31.1	Certification of Chief Executive Officer Pursuant to Rules 13a-14(a) and 15d-14(a) under the Securities Exchange Act of 1934, as amended. Filed herewith.
31.2	Certification of Chief Financial Officer Pursuant to Rules 13a-14(a) and 15d-14(a) under the Securities Exchange Act of 1934, as amended. Filed herewith.