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

                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934
                               (Amendment No.   1   )*
                                             -------

                             ESCO Technologies Inc.
- --------------------------------------------------------------------------------
                                (Name of Issuer)

                                  Common Stock
- --------------------------------------------------------------------------------
                         (Title of Class of Securities)


                                    296315104
                  ---------------------------------------------
                                 (CUSIP Number)

                                October 31, 2003
             -------------------------------------------------------
             (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 10 pages




- ------------------------                                ------------------------
CUSIP No. 296315104                   13G                 Page 2 of 10 Pages
- ------------------------                                ------------------------


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

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

- --------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                   (a) [ ]
            Not Applicable                                         (b) [ ]

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


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

            Delaware

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

                                None
      SHARES
                     -----------------------------------------------------------
                       6    SHARED VOTING POWER
    BENEFICIALLY
                                1,354,000

     OWNED BY        -----------------------------------------------------------
                       7    SOLE DISPOSITVE POWER

       EACH                     None

                     -----------------------------------------------------------
     REPORTING         8    SHARED DISPOSITIVE POWER

                                1,354,000
    PERSON WITH
- --------------------------------------------------------------------------------
  9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            1,354,000

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

           10.6%

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

           IA

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





- ------------------------                                ------------------------
CUSIP No. 296315104                   13G                 Page 3 of 10 Pages
- ------------------------                                ------------------------


- --------------------------------------------------------------------------------
  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*
                                                                   (a) [ ]
            Not Applicable                                         (b) [ ]

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


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

            Delaware

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

                                None
      SHARES
                     -----------------------------------------------------------
                       6    SHARED VOTING POWER
    BENEFICIALLY
                                1,354,000

     OWNED BY        -----------------------------------------------------------
                       7    SOLE DISPOSITVE POWER

       EACH                     None

                     -----------------------------------------------------------
     REPORTING         8    SHARED DISPOSITIVE POWER

                                1,354,000
    PERSON WITH
- --------------------------------------------------------------------------------
  9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            1,354,000

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

           10.6%

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

           CO

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







- ------------------------                                ------------------------
CUSIP No. 296315104                   13G                 Page 4 of 10 Pages
- ------------------------                                ------------------------


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

            Columbia Acorn Trust

- --------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                   (a) [ ]
            Not Applicable                                         (b) [ ]

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


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

            Massachusetts

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

                                None
      SHARES
                     -----------------------------------------------------------
                       6    SHARED VOTING POWER
    BENEFICIALLY
                                1,133,000

     OWNED BY        -----------------------------------------------------------
                       7    SOLE DISPOSITVE POWER

       EACH                     None

                     -----------------------------------------------------------
     REPORTING         8    SHARED DISPOSITIVE POWER

                                1,133,000
    PERSON WITH
- --------------------------------------------------------------------------------
  9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            1,133,000

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

           8.9%

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

           IV

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





Item 1(a)      Name of Issuer:

                    ESCO Technologies Inc.


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

                    8888 Ladue Road
                    Ste. 200
                    St. Louis, MO 63124-2090


Item 2(a)      Name of Person Filing:

                    Columbia Wanger Asset Management, L.P. ("WAM")
                    WAM Acquisition GP, Inc., the general partner of WAM
                     ("WAM GP")
                    Columbia 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:

                    296315104

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 October 31, 2003):

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

                         1,354,000

                    (b)  Percent of class:

                         10.6% (based on 12,793,817 shares outstanding as of
                         July 31, 2003).

                    (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: 1,354,000

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

                         (iv)  shared power to dispose or to direct disposition
                               of: 1,354,000

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 person 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:  November 10, 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
                                        COLUMBIA 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.

                                       COLUMBIA 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  November 10,  2003 by
                    and among Columbia Wanger Asset  Management,  L.P., WAM
                    Acquisition  GP, Inc. and Columbia Acorn Trust



                               Page 9 of 10 Pages



                                                                       EXHIBIT 1

                             JOINT FILING AGREEMENT

     The undersigned hereby agree to the joint filing of the Schedule 13G to
which this Agreement is attached.

               Dated:  November 10, 2003


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



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

                                       COLUMBIA ACORN TRUST



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

                              Page 10 of 10 pages