He joined UC Berkeley as an associate professor in 1993. From April 1993 to May 1995, he served as Deputy Assistant Secretary for Economic Policy at the U.S. Department of the Treasury in Washington, D.C. He served under As an official in the Treasury Department in the Clinton administration, he worked on the 1993 federal budget, the unsuccessful health care reform effort, and on other policies, and on several trade issues, including the Uruguay Round of the General Agreement on Tariffs and Trade and the North American Free Trade Agreement. He became a full professor at Berkeley in 1997 and has been there ever since.