QuickLinks -- Click here to rapidly navigate through this document

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


FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER PURSUANT TO RULE 13a-16 OR 15d-16
UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of October 2006   Commission File Number: 1-31349
 

THE THOMSON CORPORATION
(Translation of registrant's name into English)

Metro Center, One Station Place
Stamford, Connecticut 06902, United States
(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F   o   Form 40-F   ý

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T
Rule 101(b)(1):                         

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T
Rule 101(b)(7):                         

Indicate by check mark whether the registrant by furnishing the information contained in this Form is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

Yes   o   No   ý

If "Yes" is marked, indicate below the file number assigned to the registrant in connection with
Rule 12g3-2(b): 82-                             .


SIGNATURES

        Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

    THE THOMSON CORPORATION

 
 
By:
/s/ Deirdre Stanley
Name: Deirdre Stanley
Title: Senior Vice President and General Counsel

Date: October 26, 2006


EXHIBIT INDEX

Exhibit Number
  Description
99.1   News release dated October 26, 2006 — Thomson Reports Third-Quarter 2006 Results



QuickLinks

SIGNATURES
EXHIBIT INDEX