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 "Fund"), with respect to the Fund's Form N-CSR for the period ended June 30, 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 Fund. Date: 9/2/03 /s/ Robert L. Kemp Robert L. Kemp President Principal Executive Officer Date: 9/2/03 /s/ Frank N. Strauss Frank N. Strauss CFO & Treasurer Principal Financial Officer