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


                                  SCHEDULE 13G


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

                             SEI INVESTMENTS COMPANY
                                (Name of Issuer)

                          Common Stock, $.01 par value
                         (Title of Class of Securities)

                                   784117 10 3
                                 (CUSIP Number)

                              See Preliminary Note
             (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

                                     375,300

        NUMBER OF
                            ----------------------------------------------------
          SHARES            6    SHARED VOTING POWER

       BENEFICIALLY                1,437,000
                            ----------------------------------------------------
                            
      OWNED BY EACH         7    SOLE DISPOSITIVE POWER

        REPORTING                    375,300
                            ----------------------------------------------------
          PERSON            8    SHARED DISPOSITIVE POWER

           WITH                    1,437,000
- --------------------------------------------------------------------------------
9       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            1,812,300
- --------------------------------------------------------------------------------
10      CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

            Not Applicable
- --------------------------------------------------------------------------------
11      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

            10.1%
- --------------------------------------------------------------------------------
12      TYPE OF REPORTING PERSON

            IN
- --------------------------------------------------------------------------------

CUSIP No.  784117 10 3

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

                   Thomas N. Tryforos

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

                                           7,802

        NUMBER OF
                            ----------------------------------------------------
          SHARES            6    SHARED VOTING POWER

       BENEFICIALLY                    1,437,000
                            ----------------------------------------------------
      OWNED BY EACH         7    SOLE DISPOSITIVE POWER

        REPORTING                          7,802
                            ----------------------------------------------------
          PERSON            8    SHARED DISPOSITIVE POWER

           WITH                        1,437,000
- --------------------------------------------------------------------------------
9       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            1,444,802
- --------------------------------------------------------------------------------

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

            Not Applicable
- --------------------------------------------------------------------------------
11      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

            8.1%
- --------------------------------------------------------------------------------
12      TYPE OF REPORTING PERSON

            IN
- --------------------------------------------------------------------------------


Preliminary  Note:  This  Statement  on Schedule  13G is the  initial  filing on
Schedule 13G by the filing persons pursuant to Rule 13d-1(c). The filing persons
previously  filed a Statement on Schedule 13D. This Schedule 13G filing  updates
certain  information  included in the prior  Schedule 13D filing.  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.



ITEM 1.       (a)   Name of Issuer:

                    SEI Investments Company

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

                    One Freedom Valley Drive
                    Oaks, PA  19456

ITEM 2.       (a)   Name of Person Filing:

                    (i)    Thomas W. Smith

                    (ii)   Thomas N. Tryforos

               (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 and Thomas N. Tryforos is a 
                    United States  citizen.

              (d)   Title of Class of Securities:

                    Common Stock, par value $.01 per share

              (e)   CUSIP Number:

                    784117 10 3

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 -- 1,812,300 shares; Thomas N. Tryforos 
                    -- 1,444,802 shares

              (b)   Thomas W. Smith -- 10.1%; Thomas N. Tryforos --8.1%

              (c)   Each of Thomas W.  Smith and Thomas N.  Tryforos  has shared
                    power to vote or to  direct  the vote  and  shared  power to
                    dispose or to direct the  disposition  of 1,437,000  shares,
                    and Thomas W.  Smith has sole  power to vote and  dispose of
                    375,300 shares and Thomas N. Tryforos has sole power to vote
                    and dispose of 7,802 shares..

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

              Messrs.  Smith and Tryforos  beneficially  own 1,538,078 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.

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.

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.







                                    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:    January 19, 1999
                                                                             
                                             /s/ Thomas W. Smith
                                            ------------------------
                                                 Thomas W. Smith


                                             /s/ Thomas N. Tryforos
                                            ------------------------
                                                 Thomas N. Tryforos




                             JOINT FILING AGREEMENT


         The  undersigned  agree that the  foregoing  Statement on Schedule 13G,
dated  January  19,  1999,  is being  filed  with the  Securities  and  Exchange
Commission on behalf of each of the undersigned pursuant to Rule 13d-1(k) 

Dated:    January 19, 1999
                              
                                                               
                                             /s/ Thomas W. Smith
                                            ------------------------
                                                 Thomas W. Smith


                                             /s/ Thomas N. Tryforos
                                            ------------------------
                                                 Thomas N. Tryforos