UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934

                               (Amendment No. 2)*

                         ITT Educational Services, Inc.
--------------------------------------------------------------------------------
                                (Name of Issuer)

                                  Common Stock
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                         (Title of Class of Securities)

                                    45068B109
                  ---------------------------------------------
                                 (CUSIP Number)

                                December 31, 2002
               ---------------------------------------------------
             (Date of Event Which Requires Filing of this Statement)

            Check the appropriate box to designate the rule pursuant
                        to which this Schedule is filed:

                                [x] Rule 13d-1(b)
                                [ ] Rule 13d-1(c)
                                [ ] Rule 13d-1(d)

*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter the
disclosures provided in a prior cover page.

The information required in 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).

                               Page 1 of 11 pages

SEC 1745 (2/92)

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CUSIP No. 45068B109                   13G                   Page 2 of 10 Pages
-------------------                                       ----------------------

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 1       NAME OF REPORTING PERSON
         S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

                  Liberty Wanger Asset Management, L.P. 36-3820584

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 2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                  Not Applicable                                          (a)[ ]

                                                                          (b)[ ]

--------------------------------------------------------------------------------
 3       SEC USE ONLY

--------------------------------------------------------------------------------
 4       CITIZENSHIP OR PLACE OF ORGANIZATION

                  Delaware

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  NUMBER OF       5       SOLE VOTING POWER

   SHARES                          None

                  --------------------------------------------------------------
 BENEFICIALLY     6       SHARED VOTING POWER


  OWNED BY                      4,412,000

                  --------------------------------------------------------------
    EACH          7       SOLE DISPOSITIVE POWER

  REPORTING                       None

                  --------------------------------------------------------------
 PERSON WITH      8       SHARED DISPOSITIVE POWER

                                   4,412,000

--------------------------------------------------------------------------------
 9       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                  4,412,000

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10       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*

                  Not Applicable                                             [ ]

--------------------------------------------------------------------------------
11       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                  9.7%

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12       TYPE OF REPORTING PERSON*

                  IA

--------------------------------------------------------------------------------

                      *SEE INSTRUCTION BEFORE FILLING OUT!

-------------------                                       ----------------------
CUSIP No. 45068B109                   13G                   Page 3 of 10 Pages
-------------------                                       ----------------------

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 1       NAME OF REPORTING PERSON
         S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

                  WAM Acquisition GP, Inc.

--------------------------------------------------------------------------------
 2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                  Not Applicable                                          (a)[ ]

                                                                          (b)[ ]

--------------------------------------------------------------------------------
 3       SEC USE ONLY

--------------------------------------------------------------------------------
 4       CITIZENSHIP OR PLACE OF ORGANIZATION

                  Delaware

--------------------------------------------------------------------------------
  NUMBER OF       5       SOLE VOTING POWER

   SHARES                          None

                  --------------------------------------------------------------
 BENEFICIALLY     6       SHARED VOTING POWER

  OWNED BY                      4,412,000

                  --------------------------------------------------------------
    EACH          7       SOLE DISPOSITIVE POWER

  REPORTING                       None

                  --------------------------------------------------------------
 PERSON WITH      8       SHARED DISPOSITIVE POWER

                                   4,412,000

--------------------------------------------------------------------------------
 9       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                  4,412,000

--------------------------------------------------------------------------------
10       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*

                  Not Applicable                                             [ ]

--------------------------------------------------------------------------------
11       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                  9.7%

--------------------------------------------------------------------------------
12       TYPE OF REPORTING PERSON*

                  CO

--------------------------------------------------------------------------------

                      *SEE INSTRUCTION BEFORE FILLING OUT!

-------------------                                       ----------------------
CUSIP No. 45068B109                   13G                   Page 4 of 10 Pages
-------------------                                       ----------------------

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 1       NAME OF REPORTING PERSON
         S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

                  Liberty Acorn Trust

--------------------------------------------------------------------------------
 2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                  Not Applicable                                          (a)[ ]

                                                                          (b)[ ]

--------------------------------------------------------------------------------
 3       SEC USE ONLY

--------------------------------------------------------------------------------
 4       CITIZENSHIP OR PLACE OF ORGANIZATION

                  Massachusetts

--------------------------------------------------------------------------------
  NUMBER OF       5       SOLE VOTING POWER

   SHARES                          None

                  --------------------------------------------------------------
 BENEFICIALLY     6       SHARED VOTING POWER

  OWNED BY                        2,760,000

                  --------------------------------------------------------------
    EACH          7       SOLE DISPOSITIVE POWER

  REPORTING                        None

                  --------------------------------------------------------------
 PERSON WITH      8       SHARED DISPOSITIVE POWER

                                   2,760,000

--------------------------------------------------------------------------------
 9       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                  2,760,000

--------------------------------------------------------------------------------
10       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*

                  Not Applicable                                             [ ]

--------------------------------------------------------------------------------
11       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                  6.1%

--------------------------------------------------------------------------------
12       TYPE OF REPORTING PERSON*

                  IV

--------------------------------------------------------------------------------

Item 1(a)         Name of Issuer:

                          ITT Educational Services, Inc.

Item 1(b)         Address of Issuer's Principal Executive Offices:

                          5975 Castle Creek Parkway N. Drive
                          P.O. Box 50466
                          Indianapolis, Indiana  46250-0466

Item 2(a)         Name of Person Filing:

                          Liberty Wanger Asset Management, L.P. ("WAM")
                          WAM Acquisition GP, Inc., the general partner of WAM
                           ("WAM GP")
                          Liberty Acorn Trust ("Acorn")

Item 2(b)         Address of Principal Business Office:

                          WAM, WAM GP and Acorn are all located at:

                          227 West Monroe Street, Suite 3000
                          Chicago, Illinois  60606

Item 2(c)         Citizenship:

                          WAM is a Delaware limited partnership; WAM GP is a
                          Delaware corporation; and Acorn is a Massachusetts
                          business trust.

Item 2(d)         Title of Class of Securities:

                          Common Stock

Item 2(e)         CUSIP Number:

                          45068B109

Item 3            Type of Person:

                          (d)      Acorn is an Investment Company under section
                                   8 of the Investment Company Act.

                          (e)      WAM is an Investment Adviser registered under
                                   section 203 of the Investment Advisers Act of
                                   1940; WAM GP is the General Partner of the
                                   Investment Adviser.

                               Page 5 of 10 pages

Item 4            Ownership (at December 31, 2002):

                          (a)      Amount owned "beneficially" within the
                                   meaning of rule 13d-3:

                                   4,412,000

                          (b)      Percent of class:

                                   9.7% (based on 45,447,164 shares outstanding
                                   as of September 30, 2002, based on Form 10-Q
                                   filed on October 18, 2002).

                          (c)      Number of shares as to which such person has:

                                             (i)      sole power to vote or to
                                                      direct the vote: none

                                            (ii)      shared power to vote or to
                                                      direct the vote: 4,412,000

                                           (iii)      sole power to dispose or
                                                      to direct the disposition
                                                      of: none

                                            (iv)      shared power to dispose or
                                                      to direct disposition of:
                                                      4,412,000

Item 5            Ownership of Five Percent or Less of a Class:

                          Not Applicable

Item 6            Ownership of More than Five Percent on Behalf of Another
                  Person:

                          The shares reported herein have been acquired on
                          behalf of discretionary clients of WAM, including
                          Acorn. Persons other than WAM and WAM GP are entitled
                          to receive all dividends from, and proceeds from the
                          sale of, those shares. Acorn is the only such persons
                          known to be entitled to all dividends from, and all
                          proceeds from the sale of, shares reported herein to
                          the extent of more than 5% of the class.

Item 7            Identification and Classification of the Subsidiary Which
                  Acquired the Security Being Reported on by the Parent Holding
                  Company:

                          Not Applicable

Item 8            Identification and Classification of Members of the Group:

                          Not Applicable

Item 9            Notice of Dissolution of Group:

                          Not Applicable

                               Page 6 of 10 Pages

Item 10          Certification:

                          By signing below I certify that, to the best of my
                  knowledge and belief, the securities referred to above were
                  acquired and are held in the ordinary course of business and
                  were not acquired and are not held for the purpose of or with
                  the effect of changing or influencing the control of the
                  issuer of the securities and were not acquired and are not
                  held in connection with or as a participant in any transaction
                  having that purpose or effect.

                               Page 7 of 10 Pages

                                    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.

Date: February 12, 2003

                  The undersigned corporation, on the date above written, agrees
                  and consents to the joint filing on its behalf of this
                  Schedule 13G in connection with its beneficial ownership of
                  the security reported herein.

                                   WAM Acquisition GP, Inc.
                                     for itself and as general partner of
                                     LIBERTY WANGER ASSET
                                     MANAGEMENT, L.P.

                                   By: /s/ Bruce H. Lauer
                                       -----------------------------------------
                                           Bruce H. Lauer
                                           Senior Vice President and Secretary

                  The undersigned corporation, on the date above written, agrees
                  and consents to the joint filing on its behalf of this
                  Schedule 13G in connection with its beneficial ownership of
                  the security reported herein.

                                   LIBERTY ACORN TRUST

                                   By: /s/ Bruce H. Lauer
                                       -----------------------------------------
                                           Bruce H. Lauer
                                           Vice President, Treasurer and
                                           Secretary

                               Page 8 of 10 Pages

                                  Exhibit Index

Exhibit 1         Joint Filing Agreement dated as of February 12, 2003 by and
                  among Liberty Wanger Asset Management, L.P., WAM Acquisition
                  GP, Inc. and Liberty Acorn Trust.

                               Page 9 of 10 Pages