AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON December 28, 2004
                                                    1933 ACT FILE NO. 333-______
                                                   1940 ACT FILE NO. 811 - 03763

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                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

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

                            REGISTRATION STATEMENT ON
                                    FORM S-6

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

                FOR REGISTRATION UNDER THE SECURITIES ACT OF 1933
                     OF SECURITIES OF UNIT INVESTMENT TRUSTS
                            REGISTERED ON FORM N-8B-2

     A.   EXACT NAME OF TRUST: CLAYMORE SECURITIES DEFINED PORTFOLIOS,
          SERIES 207

     B.   NAME OF DEPOSITOR: CLAYMORE SECURITIES, INC.

     C.   COMPLETE ADDRESS OF DEPOSITOR'S PRINCIPAL EXECUTIVE OFFICES:

                            Claymore Securities, Inc.
                            2455 Corporate West Drive
                              Lisle, Illinois 60532

     D.   NAME AND COMPLETE ADDRESS OF AGENT FOR SERVICE:

  Copies to:

      NICHOLAS DALMASO, ESQ.                 ERIC F. FESS
      Senior Managing Director and
      General Counsel
      Claymore Securities, Inc.             Chapman and Cutler LLP
      2455 Corporate West Drive             111 West Monroe Street
      Lisle, Illinois  60532                Chicago, Illinois 60603
      (630) 505-3736                        (312) 845-3000

   It is proposed that this filing will become effective (check appropriate box)

     o    immediately upon filing pursuant to paragraph (b)

     o    on (date) pursuant to paragraph (b)

     o    60 days after filing pursuant to paragraph (a)

     o    on (date) pursuant to paragraph (a) of rule 485 or 486

   This post-effective amendment designates a new effective date for a
previously filed post-effective amendment.

     E.   TITLE OF SECURITIES BEING REGISTERED: Units of fractional undivided
          beneficial interest.

     F.   APPROXIMATE DATE OF PROPOSED SALE TO PUBLIC:  As soon as practicable
                                                        after the effective date
                                                        of the Registration
                                                        Statement.

   / /   Check box if it is proposed that this filing will become effective on
         (date) at (time) pursuant to Rule 487.

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The registration hereby amends this Registration Statement on such date or dates
as may be necessary to delay its effective date until the registrant shall file
a further amendment which specifically states that this Registration Statement
shall thereafter become effective in accordance with Section 8(a) of the
Securities Act of 1933 or until the Registration Statement shall become
effective on such date as the Commission, acting pursuant to said Section 8(a)
may determine.



                 PRELIMINARY PROSPECTUS DATED December 28, 2004

                              SUBJECT TO COMPLETION
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[LOGO OMITTED]

Claymore Securities Defined Portfolios, Series 207

Claymore Municipal Portfolio (2011-2015), Series 3
Claymore Municipal Portfolio (2015-2020), Series 5
Claymore New York Municipal Portfolio (2015-2020), Series 4
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         A final prospectus for a prior Series of the Claymore Securities
Defined Portfolios is hereby incorporated by reference and used as part of a
preliminary prospectus for Claymore Securities Defined Portfolios, Series 207
(the "Trust"). The final prospectus for the Trust is expected to be
substantially similar to the previous prospectus. However, specific information
with respect to the Trust, including pricing, the size and composition of the
Trust's portfolio, the number of units of the Trust, dates and summary
information regarding the characteristics of securities to be deposited in the
Trust is not now available and will be different from that shown since Trust has
a unique portfolio. Accordingly, the information contained herein with regard to
the previous Trust should be considered as being included for informational
purposes only.

         The Securities and Exchange Commission has not approved or disapproved
these securities or passed upon the adequacy of this Prospectus. Any
representation to the contrary is a criminal offense.

         The information in this Prospectus is not complete and may be changed.
We may not sell these securities until the registration statement filed with the
Securities and Exchange Commission is effective. This Prospectus is not an offer
to sell the securities and it is not soliciting an offer to buy these securities
in any state where the offer or sale is not permitted.

Incorporated herein by reference is the prospectus from Claymore Securities
Defined Portfolio, Series 188 (Registration No. 333-118161) dated September 27,
2004 and Claymore Securities Defined Portfolio, Series 199 (Registration No.
333-119960) dated December 1, 2004 which shall be used as a preliminary
prospectus for Claymore Securities Defined Portfolio, Series 207. The final
prospectus for Claymore Securities Defined Portfolio, Series 188, was filed
pursuant to Rule 497 under the Securities Act on September 29, 2004. The final
prospectus for Claymore Securities Defined Portfolio, Series 199, was filed
pursuant to Rule 497 under the Securities Act on December 3, 2004.





                       CONTENTS OF REGISTRATION STATEMENT

     A.   Bonding Arrangements of Depositor:

        The Depositor has obtained the following Securities Dealer Blanket Bond
for its officers, directors and employees:

                    INSURER/POLICY NO.                       AMOUNT

               National Union Fire Insurance
            Company of Pittsburgh, Pennsylvania             $250,000
                         959-9000

        This Registration Statement comprises the following papers and
documents.

                  The Facing Sheet
                  The Prospectus
                  The Signatures
                  Consents of Counsel


        The following exhibits:

     1.1  Reference Trust Agreement (to be supplied by amendment).

   1.1.1  Standard Terms and Conditions of Trust (Reference is made to Exhibit
          1.1.1 to Amendment No.1 to the Registration Statement on Form S-6 for
          Claymore Securities Defined Portfolios, Series 118 (File No. 333-81826
          filed on February 6, 2002).

     2.1  Code of Ethics (Reference is made to Exhibit 2.1 to the Registration
          Statement on Form S-6 for Claymore Securities Deferred Portfolios,
          Series 171 (File No. 333-112575 filed on February 19, 2004).

     3.1  Opinion of counsel as to legality of the securities being registered
          including a consent to the use of its name in the Registration
          Statement (to be supplied by amendment).

     3.2  Opinion of counsel as to Federal Income tax status of the securities
          being registered including a consent to the use of its name in the
          Registration Statement (to be supplied by amendment).

  3.3(a)  Opinion of counsel as to New York Income tax status of the
          securities being registered including a consent to the use of its name
          in the Registration Statement (to be supplied by amendment).

  3.3(b)  Opinion of counsel as to New York Income tax status of the
          securities being registered including a consent to the use of its name
          in the Registration Statement (to be supplied by amendment).

     3.4  Opinion of counsel as to the Trustee and the Trust (s) including a
          consent to the use of its name in the Registration Statement (to be
          supplied by amendment).

     4.1  Consent of Independent Registered Public Accounting Firm (to be
          supplied by amendment).




                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, the
Registrant, Claymore Securities Defined Portfolios, Series 207 has duly caused
this to the Registration Statement to be signed on its behalf by the undersigned
thereunto duly authorized, in the City of Lisle, and State of Illinois, on the
30th day of December, 2004.

                  CLAYMORE SECURITIES DEFINED PORTFOLIOS, SERIES 207, Registrant

                                        By: CLAYMORE SECURITIES, INC., Depositor

                                                        By: /s/ Nicholas Dalmaso
                                                            --------------------
                                                                Nicholas Dalmaso

         Pursuant to the requirements of the Securities Act of 1933, this
amended Registration Statement has been signed below on December 28, 2004 by the
following persons, who constitute a majority of the Board of Directors of
Claymore Securities, Inc.



     SIGNATURE*                           TITLE**                               DATE
                                                                          
                                                                            )    By:    /s/ Nicholas Dalmaso
                                                                                        --------------------
                                                                            )                  Nicholas Dalmaso
                                                                            )                  Attorney-in-Fact*
                                                                            )
DAVID HOOTEN*                             Chairman of the Board of          )           December 28, 2004
                                          Directors                         )
                                                                            )

/S/ CHARLES MILLINGTON                    Chief Financial Officer                       December 28, 2004
- ----------------------
    CHARLES MILLINGTON

/S/ NICHOLAS DALMASO                      Executive Vice President,                     December 28, 2004
- --------------------
    NICHOLAS DALMASO                      Secretary, Treasurer and
                                          Director


     *    An executed copy of the related power of attorney was filed as Exhibit
          6.0 to Registration Statement No. 333-98345 on August 22, 2002.

     **   The titles of the persons named herein represent their capacity in and
          relationship to Claymore Securities, Inc., the Depositor.




            CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

         The consent of Grant Thornton LLP to the use of its report and to the
reference to such firm in the Prospectus included in the Registration Statement
will be filed as Exhibit 4.1 to the Registration Statement.

                        CONSENT OF CHAPMAN AND CUTLER LLP

        The consent of Chapman and Cutler LLP to the use of its name in the
Prospectus included in the Registration Statement will be contained in its
opinions to be filed as Exhibits 3.1 and 3.2 to the Registration Statement.

                      CONSENT OF EMMET, MARVIN & MARTIN LLP

        The consent of Emmet, Marvin & Martin LLP to the use of its name in the
Prospectus included in the Registration Statement will be contained in its
opinions to be filed as Exhibits 3.3 and 3.4 to the Registration Statement.

                                   MEMORANDUM

        Re: Claymore Securities Defined Portfolios, Series 207

        The list of securities comprising the trust of the fund, the evaluation,
record and distribution dates and other changes pertaining specifically to the
new series, such as size and number of units of the trust in the fund and the
statement of financial condition of the new fund will be filed by amendment.

                                    1940 ACT

                              FORMS N-8A AND N-8B-2

        Form N-8A and Form N-8B-2 were filed in respect of Claymore Securities
Defined Portfolios, Series 116 (and subsequent series) (File No. 811-03763).

                                    1933 ACT

                                  THE INDENTURE

        The form of the proposed Standard Terms and Conditions of Trust is
expected to be in all respects consistent with the form of the Standard Terms
and Conditions of Trust dated February 6, 2002 relative to Claymore Securities
Defined Portfolios, Series 118.

                                                          CHAPMAN AND CUTLER LLP

Chicago, Illinois
December 28, 2004

Securities and Exchange Commission
December 28, 2004