The head of a large insurer has decided to step down.

John Boscia, now the chairman and chief executive officer of Lincoln National Corp., Philadelphia, will retire Sept. 1, the company says.

J. Patrick Barrett, a longtime director and head of a private investment firm, will take over as chairman, and Dennis Glass, the company’s president and chief operating officer, will take over as CEO, Lincoln National says.

Glass was president of Jefferson Pilot Corp., Greensboro, N.C., when Lincoln National took over that company in April 2006.

Boscia will be available to help Barrett and Glass until he retires, but Barrett and Glass “will assume their new responsibilities immediately,” Lincoln National says.

Boscia, who took over as CEO of Lincoln National 10 years ago, says he is retiring because the company is doing well and has met the milestones associated with the integration of Lincoln National and Jefferson Pilot.

“I concluded that a quick and complete transition is in the best interest of the company,” Boscia says in a statement about his decision to retire.

Glass, Lincoln National’s incoming CEO, also is chairman elect of the American Council of Life Insurers, Washington, and co-chair of the ACLI’s principles-based reserving committee.

Barrett is best known as a former chairman of Avis Inc. who arranged for the company to be purchased by an employee stock ownership plan.