EXHIBIT 32

CERTIFICATION UNDER SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 (18 U.S.C. Section 1350), the undersigned certifies that (1) this Annual Report of W. R. Grace & Co. (the “Company”) on Form 10-K for the period ended December 31, 2007, as filed with the Securities and Exchange Commission on the date hereof (this “Report”), fully complies with the requirements of Sections 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended, and (2) the information contained in this Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

/s/ Alfred E. Festa

President and Chief Executive Officer

/s/ Robert M. Tarola

Senior Vice President and Chief Financial Officer

Date: February 29, 2008

A signed original of this written statement required by Section 906 has been provided to the Company and will be retained by the Company and furnished to the Securities and Exchange Commission or its staff upon request.