Executive search firm Heidrick & Struggles International Inc. (NASD: HSII) acquired Senn-Delaney Leadership Consulting Group LLC for $53.3 million plus a possible earn-out of $15.0 million based on earnings in the first three years. The deal also includes a $6.5 million retention escrow that will be paid to key executives if they remain for three years after the acquisition.

Senn-Delaney Leadership Consulting provides “corporate culture shaping” services. Corporate culture shaping includes a comprehensive approach to shifting a company’s culture that includes changing the behaviors of individuals and teams.

“Culture shaping is a service that appeals directly to our target market — C-suite and board-level executives — making it a highly complementary offering to our premium executive search and leadership consulting services,” said Heidrick CEO L. Kevin Kelly.

Senn Delaney has projected revenue of approximately $29 million for 2012. It will continue to operate from its Huntington Beach, Calif., headquarters after the deal as a subsidiary of Heidrick. Senn Delaney President and CEO Jim Hart will report to Eric Olson, Heidrick’s global managing partner of leadership consulting. Larry Senn, founder and the current chairman of Senn Delaney, and other key executives are expected to remain with the company for a minimum of three years.

“Senn Delaney’s strength is its proven track record of successfully aligning senior teams and engaging entire organizations to create thriving, high-performance cultures,” Kelly said in a conference call. “It has been effective, for example, in working with companies in instances where management is looking to align new leaders or newly configured leadership teams and/or in the need to help integrate mergers.”