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

                                  SCHEDULE 13G

                    UNDER THE SECURITIES EXCHANGE ACT OF 1934
                               (AMENDMENT NO. 7)*

                             SEI INVESTMENTS COMPANY
                                (Name of Issuer)

                          COMMON STOCK, $.01 PAR VALUE
                         (Title of Class of Securities)

                                   784117 10 3
                                 (CUSIP Number)

                                DECEMBER 31, 2004
             (Date of Event which Requires filing of this Statement)

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

[ ] Rule 13d-1(b)
[X] 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).



CUSIP No.  784117 10 3

--------------------------------------------------------------------------------
      1     NAMES OF REPORTING PERSONS
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (entities only)

                  THOMAS W. SMITH

--------------------------------------------------------------------------------
      2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP             (a) [ ]
                                                                         (b) [X]

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

--------------------------------------------------------------------------------
      4     CITIZEN OR PLACE OF ORGANIZATION

                  UNITED STATES

--------------------------------------------------------------------------------
                        5     SOLE VOTING POWER

                                    1,273,050
     NUMBER OF
      SHARES            --------------------------------------------------------
   BENEFICIALLY         6     SHARED VOTING POWER
   OWNED BY EACH
     REPORTING                      5,538,875
      PERSON
       WITH             --------------------------------------------------------
                        7     SOLE DISPOSITIVE POWER

                                    1,948,372

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

                                    5,538,875

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

                  7,487,247

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

                  NOT APPLICABLE

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

                  7.3%

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

                  IN

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

                                     - 2 -


CUSIP No.  784117 10 3

--------------------------------------------------------------------------------
      1     NAMES OF REPORTING PERSONS
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (entities only)

                  SCOTT J. VASSALLUZZO

--------------------------------------------------------------------------------
      2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP             (a) [ ]
                                                                         (b) [X]

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

      3     SEC USE ONLY

--------------------------------------------------------------------------------
      4     CITIZEN OR PLACE OF ORGANIZATION

                  UNITED STATES

--------------------------------------------------------------------------------
                        5     SOLE VOTING POWER

                                    0
    NUMBER OF
     SHARES             --------------------------------------------------------
  BENEFICIALLY          6     SHARED VOTING POWER
  OWNED BY EACH
    REPORTING                       5,488,875
     PERSON
      WITH              --------------------------------------------------------
                        7     SOLE DISPOSITIVE POWER

                                    0

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

                                    5,488,875

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

      9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                  5,488,875

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

                  NOT APPLICABLE

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

                  5.4%

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

                  IN

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

                                     - 4 -


CUSIP No.  784117 10 3

--------------------------------------------------------------------------------
      1     NAMES OF REPORTING PERSONS
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (entities only)

                  DANIEL J. ENGLANDER

--------------------------------------------------------------------------------
      2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP             (a) [ ]
                                                                         (b) [X]

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

--------------------------------------------------------------------------------
      4     CITIZEN OR PLACE OF ORGANIZATION

                  UNITED STATES

--------------------------------------------------------------------------------
                        5     SOLE VOTING POWER

                                    8,000
    NUMBER OF
     SHARES             --------------------------------------------------------
  BENEFICIALLY          6     SHARED VOTING POWER
  OWNED BY EACH
    REPORTING                       50,000
     PERSON
      WITH              --------------------------------------------------------
                        7     SOLE DISPOSITIVE POWER

                                    8,000

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

                                    50,000

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

                  58,000

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

                  NOT APPLICABLE

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

                  0.1%

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

                  IN

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

                                     - 5 -


Explanatory Note: This Amendment No. 7 on Schedule 13G is being filed (i)
pursuant to Rule 13d-2(b) of the Securities Exchange Act of 1934, as amended,
to reflect changes in the information reported in the previous filing, and (ii)
to reflect the removal of Thomas N. Tryforos as a joint filer based on the fact
that, as of December 31, 2004, Mr. Tryforos no longer beneficially owns more
than five percent of the issuer's common stock.

ITEM 1. (a)    NAME OF ISSUER:

               SEI Investments Company

        (b)    ADDRESS OF ISSUER'S PRINCIPAL EXECUTIVE OFFICES:

               1 Freedom Valley Drive
               Oaks, PA 19456-1100

ITEM 2. (a)    NAME OF PERSON FILING:

               (i) Thomas W. Smith

               (ii) Scott J. Vassalluzzo

               (iii) Daniel J. Englander

               The filing of this Statement shall not be deemed to be an
               admission that the filing persons comprise a "group" within the
               meaning of Section 13(d)(3) of the Securities Exchange Act of
               1934, as amended. The Reporting Persons each disclaim beneficial
               ownership of the shares reported in this Schedule 13G in excess
               of those shares as to which they have or share voting or
               investment authority.

        (b)    ADDRESS OF PRINCIPAL BUSINESS OFFICE:

               The following is the address of the principal business office of
               each of the filing persons:

               323 Railroad Avenue
               Greenwich, CT 06830

        (c)    CITIZENSHIP:

               Each of Messrs. Thomas W. Smith, Scott J. Vassalluzzo and Daniel
               J. Englander is a United States citizen.

        (d)    TITLE OF CLASS OF SECURITIES:

               Common Stock, par value $.01 per share.

        (e)    CUSIP NUMBER:

               784117 10 3

                                     - 6 -


ITEM 3. IF THIS STATEMENT IS FILED PURSUANT TO RULES 13d-1(b) OR 13d-2(b) OR
        (c), CHECK WHETHER THE PERSON FILING IS A:

        Not applicable.

        IF THIS STATEMENT IS FILED PURSUANT TO RULE 13d-1(c), CHECK THIS BOX [X]

ITEM 4. OWNERSHIP

        (a)    Thomas W. Smith - 7,487,247 shares; Scott J. Vassalluzzo - 
               5,488,875 shares; Daniel J. Englander - 58,000

        (b)    Thomas W. Smith - 7.3%; Scott J. Vassalluzzo - 5.4%; Daniel J.
               Englander - 0.1%

        (c)    Messrs. Thomas W. Smith and Daniel J. Englander have the sole
               power to vote or to direct the vote of 1,273,050 and 8,000
               shares, respectively and have the sole power to dispose or to
               direct the disposal of 1,948,372 and 8,000 shares, respectively.
               Mr. Scott J. Vassalluzzo has the sole power to vote or dispose or
               to direct the vote or disposal of no shares. Messrs. Thomas W.
               Smith, Scott J. Vassalluzzo and Daniel J. Englander have the
               shared power to vote or to direct the vote and shared power to
               dispose or to direct the disposition of 5,538,875, 5,488,875 
               and 50,000 shares, respectively.

ITEM 5. OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS

        As of December 31, 2004, Thomas N. Tryforos ceased to beneficially own
        more than five percent of the outstanding common stock of the Issuer.

ITEM 6. OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON

        Messrs. Smith, Vassalluzzo and Englander in the aggregate beneficially
        own 6,387,247 shares in their capacities as investment managers for
        certain managed accounts. The managed accounts have the right to receive
        dividends from, and the proceeds from the sale of, the managed accounts'
        shares. Voting and investment authority over investment accounts
        established for the benefit of certain family members and friends of the
        Reporting Persons is subject to each beneficiary's right, if so
        provided, to terminate or otherwise direct the disposition of the
        Managed Account.

ITEM 7. IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH ACQUIRED THE
        SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY

        Not applicable.

                                     - 7 -


ITEM 8. IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP

        Not applicable.

ITEM 9. NOTICE OF DISSOLUTION OF GROUP

        Not applicable.

ITEM 10.CERTIFICATION

        By signing below, I certify that, to the best of my knowledge and
        belief, the securities referred to above 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.

                                     - 8 -

                                    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 14, 2005

                                                        /s/ Thomas W. Smith
                                                   -----------------------------
                                                          Thomas W. Smith

                                                     /s/ Scott J. Vassalluzzo
                                                   -----------------------------
                                                       Scott J. Vassalluzzo

                                                      /s/ Daniel J. Englander
                                                   -----------------------------
                                                        Daniel J. Englander

                                     - 9 -


                             JOINT FILING AGREEMENT

      The undersigned agree that the foregoing Statement on Schedule 13G, dated
February 14, 2005, is being filed with the Securities and Exchange Commission
on behalf of each of the undersigned pursuant to Rule 13d-1(k)

Dated: February 14, 2005

                                                     /s/ Thomas W. Smith
                                              ----------------------------------
                                                        Thomas W. Smith

                                                   /s/ Scott J. Vassalluzzo
                                              ----------------------------------
                                                     Scott J. Vassalluzzo

                                                    /s/ Daniel J. Englander
                                              ----------------------------------
                                                      Daniel J. Englander

                                     - 10 -