-Resident fellow, 1990-2003, and W. H. Brady Scholar, 2003-present, AEI
-Field research and lectures in the United Kingdom, 1986, 1989, 1993, 1994, 1996, 1998, 2003
-Consultant, Organization for Economic Co-operation and Development (OECD), France, 1991
-Work and field research, Thailand, 1972-1973, 1979, 1983, 1991
-Consultant, Bulgarian government, 1990
-Senior Fellow, Manhattan Institute for Policy Research, 1982-1990
-Chief scientist, 1979-1981, Research scientist (evaluation of social programs), 1974-1979, American Institutes for Research (AIR)
-Field research, Ethiopia, Nigeria, and Senegal, 1974
-Volunteer, Peace Corps; Contractor, USAID, Thailand, 1965-1970