**Exhibit 31.3**CERTIFICATION UNDER EXCHANGE ACT RULE 13A-14 AND 15D-14I, William R. McClayton, certify that:1. I have reviewed this annual report on Form 10-K of DiamondCluster International, Inc; 2. Based on my knowledge, this annual report does not contain any untrue statement of amaterial fact or omit to state a material fact necessary to make the statements made, in light ofthe circumstances under which such statements were made, not misleading with respect to theperiod covered by this annual report; 3. Based on my knowledge, the financial statements, and other financial information included inthis annual report, fairly present in all material respects the financial condition, resultsof operations and cash flows of the registrant as of, and for, the periods presented in thisannual report; 4. The registrant’s other certifying officers and I are responsible for establishing andmaintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules13-15(f) and 15d-15(f)) for the registrant and we have: a) Designed such disclosure controls and procedures, or caused such disclosure controls andprocedures to be designed under our supervision, to ensure that material informationrelating to the registrant, including its consolidated subsidiaries, is made known to us byothers within those entities, particularly during the period in which this annual report isbeing prepared;  b) Designed such internal control over financial reporting, or caused such internal controlover financial reporting to be designed under our supervision, to provide reasonableassurance regarding the reliability of financial reporting and the preparation of financialstatements for external purposes in accordance with generally accepted accountingprinciples;  c) Evaluated the effectiveness of the registrant’s disclosure controls and proceduresand presented in this report our conclusions about the effectiveness of the disclosurecontrols and procedures, as of the end of the period covered by this report based on suchevaluation; and  d) Disclosed in this report any change in the registrant’s internal control over financialreporting that occurred during the registrant’s most recent fiscal quarter (the registrant’sfourth fiscal quarter in the case of an annual report) that has materially affected, or isreasonably likely to materially affect, the registrant’s internal control over financialreporting.5. The registrant’s other certifying officers and I have disclosed, based on our most recentevaluation of internal control over financial reporting, to the registrant’s auditors and theaudit committee of registrant’s board of directors (or persons performing the equivalentfunctions): a) All significant deficiencies and material weaknesses in the design or operation ofinternal controls over financial reporting which are reasonably likely to adversely affectthe registrant’s ability to record, process, summarize and report financial information;and  b) Any fraud, whether or not material, that involves management or other employees whohave a significant role in the registrant’s internal controls over financial reporting.Date: June 14, 2006/s/William R. McClayton