**EXHIBIT 31.(i).1**

CERTIFICATION OFPERIODIC REPORT UNDER SECTION 302 OFTHE SARBANES-OXLEY ACT OF 2002

I, A. E. Festa, certifythat:

1.     I have reviewed thisquarterly report on Form 10-Q of W. R. Grace & Co.;

2.     Based on my knowledge, thisreport does not contain any untrue statement of a material fact or omit tostate a material fact necessary to make the statements made, in light of thecircumstances under which such statements were made, not misleading withrespect to the period covered by this report;

3.     Based on my knowledge, thefinancial statements, and other financial information included in this report,fairly present in all material respects the financial condition, results ofoperations and cash flows of the registrant as of, and for, the periods presentedin this report;

4.     The registrant’s othercertifying officer(s) and I are responsible for establishing and maintainingdisclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e)and 15d-15(e)) and internal control over financial reporting (as defined inExchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a)   designed such disclosurecontrols and procedures, or caused such disclosure controls and procedures tobe designed under our supervision, to ensure that material information relatingto the registrant, including its consolidated subsidiaries, is made known to usby others within those entities, particularly during the period in which thisreport is being prepared;

(b)   designed such internal controlover financial reporting, or caused such internal control over financialreporting to be designed under our supervision, to provide reasonable assuranceregarding the reliability of financial reporting and the preparation offinancial statements for external purposes in accordance with generallyaccepted accounting principles;

(c)   evaluatedthe effectiveness of the registrant’s disclosure controls and procedures andpresented in this report our conclusions about the effectiveness of thedisclosure controls and procedures, as of the end of the period covered by thisreport based on such evaluation; and

(d)   disclosed in this report anychange in the registrant’s internal control over financial reporting thatoccurred during the registrant’s most recent fiscal quarter (the registrant’sfourth fiscal quarter in the case of an annual report) that has materiallyaffected, or is reasonably likely to materially affect, the registrant’sinternal control over financial reporting; and

5.     The registrant’s othercertifying officer(s) and I have disclosed, based on our most recent evaluationof internal control over financial reporting, to the registrant’s auditors andthe audit committee of the registrant’s board of directors (or personsperforming the equivalent functions):

(a)   allsignificant deficiencies and material weaknesses in the design or operation ofinternal control over financial reporting which are reasonably likely toadversely affect the registrant’s ability to record, process, summarize andreport financial information; and

(b)   any fraud, whether or notmaterial, that involves management or other employees who have a significantrole in the registrant’s internal control over financial reporting.
| Date: May 9, 2007 |                     |
|-------------------|--------------------------|
|              | /s/ A. E. Festa          |   |
|              | A. E. Festa              |
|              | President and            |
|              | Chief Executive  Officer |

 

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