Postdoctoral fellow in psychiatry and pharmacology University Chicago, 1970-1972. Research associate in psychiatry Duke University, Durham, North Carolina, 1972-1973. Assistant professor pharmacology Medical College Virginia, Richmond, 1973-1978, associate professor, 1978-1984, professor pharmacology, 1984—2003, Luther A Butler professor pharmacology, since 2003.
Director Institute for Drug and Alcohol Studies, since 1993. Coordinator Humphrey Fellowship Program in Substance Abuse, since 2006. Founder co director International Program Addiction Studies, since 2008.
Chairman Drug Abuse Advisory Committee, Food and Drug Administration, Rockville, Maryland, 1983-1984. Member Robert Wood Johnson Research Network on Etiology of Tobacco Dependence, 1997-2006. Member advisory board Partnership for Drug Free American.
Fellow College on Problems of Drug Dependence (charter fellow, president 1995-1996), American College Neuropsychopharmacology, American Psychological Association (president psychopharmacology division 1989-1990, chair board science affairs 1995-1996, Distinguished Service to Psychological Science award, 2006, Brady-Schuster award 2007, board member 1994-1996, since 2008). Member European Behavioral Pharmacology Society (council member 1986-1994).