Professor Emeritus, 1994–present; John M. Olin University Professor, 1986–94; Professorial Lecturer, 1979–86, Georgetown University

Visiting Professor of Political Science, University of Chicago, 1984 and 1989

Member, National Council on the Humanities, National Endowment for the Humanities, 1982–88

Member, Board of Directors, Institute for Educational Affairs, 1980–88

Member, Joint Committee Project ’87, Joint Undertaking of the American Historical Association and American Political Science Association to Commemorate the Bicentennial of the US Constitution, 1987

Lecturer, Phi Beta Kappa Society Lecture Series, 1985–86

Member, Council of Scholars, Library of Congress, 1981–85

Professorial Lecturer, Georgetown University, 1979–86

Guggenheim Fellow, 1978–79

Professor of Political Science, University of Toronto, 1970–79

Visiting Charles Evans Hughes Professor of Political Science, Colgate University, 1970

Visiting Professor of Political Science, University of Toronto, 1969

Chairman, Department of Government, Cornell University, 1963–67

Fulbright Fellow; Rockefeller Fellow, 1965–66

Associate Professor and Professor of Government, Cornell University, 1959–69

Lecturer, Salzburg Seminar in American Studies, 1959

Assistant Professor of Political Science, Yale University, 1956–59

Assistant Professor of Political Science, Louisiana State University, 1953–56

Carnegie Teaching Fellow, 1952–53