EX-99.906CERT Registrant Name: CGM Capital Development Fund File Number: 811-933 Registrant CIK Number: 0000060332 Certification pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 The undersigned officers of the CGM Capital Development Fund (the "Registrant "), with respect to the Fund's Form N-CSR for the period ended December 31, 2003 as filed with the Securities and Exchange Commission, each hereby certify that, to the best of such officer's knowledge: 1. the Fund's Form N-CSR fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934; and 2. the information contained in such Form N-CSR fairly presents, in all material respects, the financial conditions and results of operations of the Registrant. Date: February 25, 2004 /s/ Robert L. Kemp Robert L. Kemp President Principal Executive Officer Date: February 25, 2004 /s/ Frank N. Strauss Frank N. Strauss CFO & Treasurer Principal Financial Officer This certification is being furnished to the Securities and Exchange Commission solely pursuant to 18 U.S.C. 1350 and is not being filed as part of the Form N-CSR filed with the Commission.