Re: Collaboration Agreement, dated as of February 6, 2007, by and between The Corporate Executive Board Company and The Advisory Board Company (the “Collaboration Agreement”)

Exhibit 10.23

February 4, 2010

Xxxxxx X. Xxxxxxx, III
Chairman of the Board and Chief Executive Officer
The Corporate Executive Board Company
0000 Xxxxx Xxxx Xxxxxx
Xxxxxxxxx, XX 00000

Re: Collaboration Agreement, dated as of February 6, 2007, by and between The Corporate Executive Board Company and The Advisory Board Company (the “Collaboration Agreement”)

Dear Xxx:

This letter confirms that The Corporate Executive Board Company (“CEB”) and The Advisory Board Company (“ABCO”) have agreed to extend the Initial NP Term and the Initial EC Term (as such terms are defined in the Collaboration Agreement) through February 5, 2012 as contemplated by Sections 3.3(a) and 3.4(a) of the Collaboration Agreement, respectively, effective as of February 4, 2010.

Please indicate your agreement with the foregoing by signing and returning one copy of this letter to my attention, which shall constitute CEB’s and ABCO’s agreement with respect to the subject matter hereof.

Very truly yours,
 

/s/ Xxxxxx X. Xxxxxxxxxxx  

Xxxxxx X. Xxxxxxxxxxx 

Chief Executive Officer 

ACCEPTED AND AGREED:
THE CORPORATE EXECUTIVE BOARD COMPANY
By:		/s/ Xxxxxx X. Xxxxxxx, III
		Xxxxxx X. Xxxxxxx, III
		Chairman of the Board and Chief Executive Officer