Founding Member and Chairman Canadian Pugwash Committee, 1960
Senior Fellow Massey College, University of Toronto, 1963
Fellow Royal Society of Canada, 1966
Fellow Royal Society of London, 1971
Honorary Foreign Member American Academy of Arts and Science, 1976
Foreign Associate National Academy of Sciences (U.S.A.), 1978
Companion Order of Canada, 1979
Member Science Advisory Board, Max Planck Institute for Quantum Optics, Germany, 1982-1992
Member Pontifical Academy of Sciences, Rome, 1986.
Knight Grand Cross Sovereign Military Order of St. John of Jerusalem "Knights of Malta," 1987
Member National Advisory Board on Science and Technology, 1987-1989
Fellow Royal Society of Edinburgh, 1988
Member of the Board Ontario Laser and Lightwave Research Centre, 1988-1992
Honorary Consultant Institute for Molecular Science, Okazaki, Japan, 1989-1994
President and Founding Member Canadian Committee of Scientists and Scholars
Founding Member Royal Society of Canada Committee on Scholarly Freedom
Member American Academy of Arts and Science Committee on International Security Studies
Member of the Board Canadian Centre for Global Security
Honorary Fellow Royal Society of Chemistry, United Kingdom, 1991
Honorary Fellow The Chemical Institute of Canada, 1991
Board Member Steacie Institute for Molecular Sciences, 1991-present
Member The Queen's Privy Council for Canada, 1992
Member Croatian Academy of Sciences and Arts, 1992
Member Board of the Premier's Council, 1994
Co-Chair International Consultative Group on Improving United Nation's Rapid Reaction Capability, 1995
Honorary Fellow Trinity College, University of Toronto, 1995
Distinguished Anniversary Fellow The Australian National University, 1996
Honorary Fellow National Institute of Chemistry, Singapore, 1997
Foreign Member Russian Academy of Sciences, 1999