February 5, 2014

Exhibit 10.18

February 5, ▇▇▇▇

▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇▇▇▇▇

▇▇▇▇▇ Executive Officer

▇▇▇▇ ▇ ▇▇▇▇▇▇ ▇▇

▇▇▇▇▇▇▇▇▇▇ ▇▇ ▇▇▇▇▇

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

Dear ▇▇▇▇▇▇:

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, 2017 as comtemplated by Sections 3.3(a) and 3.4(a) of the Collaboration Agreement, respectively, effective as of the date hereof.

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/ ▇▇▇ ▇▇▇▇▇▇▇

▇▇▇ ▇▇▇▇▇▇▇

Chairman of the Board and

Chief Executive Officer

ACCEPTED AND AGREED:

THE ADVISORY BOARD COMPANY

By:		/s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇▇▇▇
		▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇▇▇▇▇
		Chief Executive Officer