Professor of History and Ethnic Studies, and Director, Center for the Study of Race and Ethnicity in America, Brown University, 2002-present Professor and Chair, Department of Ethnic Studies, University of Colorado at Boulder, 1996-2002 Director, Center for Studies of Ethnicity and Race in America (CSERA), University of Colorado at Boulder, 1988-2002 Visiting Professor, Wesleyan University (CT), 2005-06. Visiting Associate Professor, Department of History, New York University, 1986 Associate Professor, Lehman College and Ph.D. Program in History, Graduate Center, C.U.N.Y., New York, New York, 1985-1988 Visiting Assistant Professor, Department of History, University of Arizona, Tucson, Arizona, Fall 1979 Instructor to Associate Professor (with tenure), Department of History, Washington University, St. Louis, Missouri, 1973-1985 University of Michigan, Ann Arbor (1972-1973, part-time) El Colegio de México, Mexico City (1971-1972, part-time)