Harvard University: Research Fellow - 1962-1964
Harvard University: Tutor - 1964
American Univ. of Beirut: Research Associate - 1964-65
American Univ. of Beirut: Assistant Professor - 1965-69
American Univ. of Beirut: Associate Professor - 1969-75
University of Colorado: Research Associate (Sabbatical (Boulder, CO) leave) 1971-72
American Univ. of Beirut: Professor - 1975-Present
Univ. of California: Visitin Professor Summer 1977 (Berkeley, CA)
University of Notre Dame: Visiting Professor (Sabbatical) - 1978-79
American Univ. of Beirut: Chairman, Dept. of Chemistry -1969-70, 1977-78, 1979-1986
University of Colorado: Visiting Professor (Sabbatical) - 1986-87(Boulder, CO)
American Univ. of Beirut: Acting Dean, Faculty of Arts - April-July 1986 & Sciences
American Univ. of Beirut: Vice President for Academic Affairs 1987-1999 And AUB representative to the Presidents of Private Universities Board advisory to H.E. Minister of Higher Education, Lebanon.
American Univ. of Beirut: Acting Deputy President, average /1987-1999 of a total of 1 month per year
Univ. of Colorado (Boulder): Research Collaboration/August 1988
Univ. of North Texas (Denton): Distinguished Visiting Professor/1990-1991 (Sabbatical)
Univ. of Colorado (Boulder): Research Collaboration/June 1991
American Univ. of Beirut: Acting Dean, Faculty of Health/April 1994 - Sciences -August 1998
American Univ. of Beirut: Acting President( very short periods)/July 19-Sept.15,1998 and several v. shorter periods.July 21- Aug.20, 1999.
Univ. of California, Davis: Visiting Scholar (Sabbatical)/ Oct.1, 1999 - Sept.1, 2000
Univ. of California, Davis: Visiting Scholar/ July1,- Aug.31,01; July1,-Aug.31,02; July1,-Aug.31,03
Univ. of California, Davis: Visiting Scholar/ July 2004- (Paid Research Leave) / Jan.2005
Univ. of California, Davis: Visiting Scholar/ July-Aug.2006 / Visiting Scholar / July-Aug. 2007 - July-Aug. 2008
Univ. of California, Davis: Visiting Scholar/July-Aug. 2009
Univ. of California at Davis: Visiting scholar/ July-Aug. 2010 Univ. of California at Davis Visiting Scholar (Paid Research Leave, Oct.-Jan.)/ July 2011-Jan.2012
Univ. of California at Davis Faculty Development –Visiting Scholar (July-Aug. 2013)
Univ. of California at Davis Visiting Scholar/July-Aug. ,2014
Acting President, AUB July 1-August 31, 2015
Acting Chief Operations Officer (COO) ,AUB July1-August 31, 2015
Senior Advisor to the President, AUB Sept.2015-Present
