As a businessman, Paul Sack’s career has been in real estate—acquiring and managing properties for investors. In 1975, he founded The RREEF Funds to facilitate such investment by large pension funds. RREEF owned and managed $95 billion of real estate at its peak and is now owned by Deutche Bank.

In 1966-7, he was country director of the Peace Corps program in Tanzania, comprised of 380 Volunteers and a professional staff of 12. In 1968-9, he worked in Peace Corps/Washington as director of the Office of Planning, Programs, and Research, which made the decisions as to which requests from overseas for Volunteers would be approved and thereby influenced the character of Peace Corps programs.

Returning to his home in San Francisco, he enrolled in the Ph.D. program of the economics department at the University of California at Berkeley, where he specialized in the economics and politics of development and secured his Ph.D. in political economy in 1975. He also holds an A.B. degree from Harvard College in economics and an MBA from the Harvard Business School.

He is an enthusiastic collector of photography and a former trustee of the San Francisco Museum of Modern Art, the San Francisco Art Institute, and the Ansel Adams Center.