Assistant Professor, University of Wisconsin, 1976-1978
Assistant Professor, Rutgers University, 1978-1980
Member, The Institute for Advanced Study, 1980-1981
Assistant Professor, Michigan State University, 1981-1982
Member, Max-Planck Institute, 1982-1983
Sloan Fellow, 1983-1985
Associate Professor, Michigan State University, 1983-1986
Member, M.S.R.I., 1984-1985, 1990-1991, Spring 1998, Spring 2004
Member, Feza Gursey Institute, Spring 1998
Member, The Institute for Advanced Study, Spring 2002, Spring 2005
Harvard University, Spring 2005
Professor, Michigan State University, 1986 - 2020