1965-1967 Research Assistant, Department of Microbiology, South Dakota State University
1967-1968 Woodrow Wilson Fellow, University of Minnesota
1968-1969 National Science Foundation Traineeship, Medical College of Virginia
1971 National Science Foundation Postdoctoral Trainee
1971-1973 Postdoctoral Fellow, Department of Cell Biology, Roche Institute of Molecular Biology
1973 Staff Fellow, Laboratory of Molecular Genetics
1973-1977 Scientist, Microbial Genetics Section, Laboratory of Molecular Genetics
1977-1981 Scientist, Virus Tumor Biology Section, Laboratory of Molecular Virology, VOP
1981-1984 Research Director, Molecular Genetics, Inc.
1984-1990 Research Leader, Molecular Genetics, Viral Diseases Group, E. I. du Pont de Nemours & Company
1991-1993 Senior Research Fellow, DuPont Merck Pharmaceutical Company
1993-2003 Professor, Department of Molecular Biology, Princeton University
2003-2004 Professor, Department of Molecular Biology, Princeton University
2003-2004 Associate Chair, Department of Molecular Biology, Princeton University
2004-2007 Professor, Department of Molecular Biology, Princeton University
2004-2007 Chair, Department of Molecular Biology, Princeton University
2007-2013 Chair, Department of Molecular Biology, Princeton University
2007-2013 Henry L. Hillman Professor, Department of Molecular Biology, Princeton University
2013- Henry L. Hillman Professor, Department of Molecular Biology,
Princeton University
Research Affiliate, Pacific Biomedical Research Center, July l983-August 1984, University of Hawaii at Manoa, Honolulu
Guest Lecturer, Department of Molecular Biology, Princeton University, 1986, 1987
Department Associate; Dept. of Molecular Biology, Princeton University, 1987 - 1993
Adjunct Associate Professor; Department of Microbiology, University of Pennsylvania, 1988-1996
Invited Lecturer, Distinguished Corporate Scientist Lecture Series, Center for Biotechnology, State University of New York at Stony Brook, January 26, 1988
Chair of DNA Viruses, Division S, ASM, 1993