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                                                                   EXHIBIT 10.24

                                 PROMISSORY NOTE

$220,000.00                                                       March 31, 2001


FOR VALUE RECEIVED, the undersigned, Scott A. Schirmeier ("Borrower"), an
employee of the Advisory Board Company with his principal residence at 2418 19th
Street, N.W. # 29, Washington, D.C., promises to pay to order of the Advisory
Board Company, a Maryland corporation with its place of business at 600 New
Hampshire Avenue, N.W., Washington, D.C., the principal sum of $220,000.00 with
interest at the rate of seven percent (7%) per annum, subject to the terms and
conditions herein contained.

        1.      The principal sum shall be due and payable on the earlier of (i)
the date the Borrower sells Advisory Board Company stock pursuant to an exercise
of Advisory Board Company options, (ii) the date the Borrower has Advisory Board
Company options repurchased by the Company, (iii) thirty days prior to the
expiration of any of the Borrower's Advisory Board Company options, or (iv) the
date the Borrower leaves the employ of the Advisory Board Company for any
reason.

        2.      Interest on the outstanding balance of the principal sum shall
accrue at the rate of seven percent (7%) per annum from March 31, 2001 until
this Note is paid in full.

        3.      This Note may be prepaid in whole or in part at any time without
penalty.

        4.      This note is secured by all real and personal property of the
Borrower.

        5.      Upon the occurrence of an Event of Default, as that term is
defined below, and the continuation of any such Event of Default for a period of
thirty days after the delivery of written notice to the undersigned setting,
forth such Event of Default, the unpaid balance of the. principal and any
interest accrued thereon shall, at the option of the holder hereof, at once
become due and payable. The notice of default shall be deemed to be delivered if
sent by United States or registered mail to the undersigned at the address set
forth above.

An Event of Default will be deemed to have occurred if:

                (a)     Debtor fails to pay the principal payments and accrued
        interest when due in accordance with the Note.

                (b)     Debtor files a voluntary proceeding under the Bankruptcy
        Code, or any involuntary petitions under the Bankruptcy Code are filed
        against the Debtor.

        6.      Any payment by the undersigned on this Note shall be credited
first to any interest then due, and the remainder on the principal sum, and
interest shall thereupon cease to accrue upon the amount so credited on the said
principal sum.



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IN WITNESS WHEREOF, the undersigned has set its hand and seal as of the day,
month and year first hereinabove written.




Creditor:                                                Debtor:

The Advisory Board Company, Inc.                         Scott A. Schirmeier


/s/Michael D'Amato                                       /s/ SCOTT A. SCHIRMEIER
-----------------------------------                      -----------------------
Michael D'Amato
Executive Vice President




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