**EXHIBIT31(a)****Rule 13a-14(a)/15d-14(a) Certification of Mr. William D. Perez.**I, William D. Perez, certify that:1. I have reviewed this annual report on Form 10-K of Wm. Wrigley Jr. Company; 2. Based on my knowledge, this report does not contain any untrue statement of amaterial fact or omit to state a material fact necessary to make the statementsmade, in light of the circumstances under which such statements were made, notmisleading with respect to the period covered by this report; 3. Based on my knowledge, the financial statements, and other financial informationincluded in this report, fairly present in all material respects the financialcondition, results of operations and cash flows of the registrant as of, and for,the periods presented in this report; 4. The registrant’s other certifying officer and I are responsible for establishingand maintaining disclosure controls and procedures (as defined in Exchange ActRules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (asdefined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant andhave: (a) Designed such disclosure controls andprocedures or caused such disclosurecontrols and procedures to bedesigned under our supervision, toensure that material informationrelating to the registrant, includingits consolidated subsidiaries, ismade known to us by others withinthose entities, particularly duringthe period in which this report isbeing prepared;  (b) Designed such internal control overfinancial reporting, or caused suchinternal control over financialreporting to be designed under oursupervision, to provide reasonableassurance regarding the reliabilityof financial reporting and thepreparation of financial statementsfor external purposes in accordancewith generally accepted accountingprinciples;  (c) Evaluated the effectiveness of theregistrant’s disclosure controls andprocedures and presented in thisreport our conclusions about theeffectiveness of the disclosurecontrols and procedures, as of theend of the period covered by thisreport based on such evaluation; and  (d) Disclosed in this report any changein the registrant’s internal controlover financial reporting thatoccurred during the registrant’s mostrecent fiscal quarter (theregistrant’s fourth quarter in thecase of an annual report) that hasmaterially affected, or is reasonablylikely to materially affect, theregistrant’s internal control overfinancial reporting; and;5. The registrant’s other certifying officer and I have disclosed, based on our mostrecent evaluation of internal control over financial reporting, to theregistrant’s auditors and the audit committee of registrant’s board of directors(or persons performing the equivalent functions): (a) all significant deficiencies andmaterial weaknesses in the design oroperation of internal control overfinancial reporting which arereasonably likely to adversely affectthe registrant’s ability to record,process, summarize and reportfinancial information; and  (b) any fraud, whether or not material,that involves management or otheremployees who have a significant rolein the registrant’s internal controlover financial reporting.Date: February 13, 2007                                      /s/ WILLIAM D. PEREZ   William D. Perez   President and Chief Executive Officer