Peter E. Haas Sr., 86, an heir to Levi Strauss & Co. who helped build the jeans company into a socially conscious clothing empire, died Dec. 3 at his home in San Francisco. He had a stroke that kept him in a wheelchair in his later years.

A great-grandnephew of Levi Strauss, Mr. Haas continued the tradition of the jeans pioneer, teaming up with his older brother, Walter A. Haas Jr., to transform the small manufacturer of Western apparel into one of the world's most famous clothing brands during his 60-year career with the company.

As president of Levi Strauss, Mr. Haas was a strong proponent of corporate social responsibility and worked for racial desegregation of apparel factories in the late 1940s and 1950s.

When the company sought to expand its operations to the South, Mr. Haas told local officials that Levi Strauss would only open manufacturing plants there if blacks in the factories were granted equal status with whites.

Peter Edgar Haas Sr. was born in San Francisco in 1918. He was the second of three children born to Elise Stern Haas and Walter A. Haas Sr., who like his father and great-uncle before him, was president of Levi Strauss.

Peter Haas was a 1940 economics graduate of the University of California at Berkeley.

Rejected from the military during World War II because of poor eyesight, Mr. Haas instead entered Harvard Business School. After graduating in 1943, he worked for a defense contractor, Hammond Aircraft, where he met his first wife, Josephine Baum.

The couple married in 1945, the same year Mr. Haas returned to the family business.

Mr. Haas and his brother, Walter, took over Levi Strauss in 1958. Five year earlier, Time magazine had named the brothers "Leaders of Tomorrow."

Under their leadership, the company capitalized on postwar demographic changes, marketing an extended line of bluejeans to young people.

By 1971, when the company went public, Levi Strauss had nearly 20,000 employees worldwide and annual sales of $405 million. The company has since gone private again.

Mr. Haas, also a well-known philanthropist, was active in the United Way, and he and his second wife, Miriam, gave millions to support the arts, public policy programs, and health and human services.

Mr. Haas also served as president of San Francisco Aid for Retarded Children. He had a developmentally disabled son from his first marriage, Michael, who died.

Mr. Haas was a donor and fundraiser for UC Berkeley. In 1989, he and his siblings gave $27 million to name the Haas School of Business in honor of their late father, who also graduated from the university.

His first marriage ended in divorce.

Survivors include his second wife; two children from his first marriage; two stepsons; four grandchildren; and a great-granddaughter.

Peter E. Haas Sr. was president of the jeansmaker.