National
Member of the Royal Swedish Academy of Sciences (KVA), 1968 - date (1:st Vice president 1986 - 1988)
Member of the Swedish National Committee for Astronomy, 1968 - 1995
Member of NFR's Committee for ESO, 1972 - 1992 (chairman 1988 - 1992)
Member of a working group that developed Sweden's first "Astronomigymnasium" (Astronomy high school), 1985 - 1989
Member of Fakultetsnämnden and Tjänsteförslagsnämnden,
Stockholm University, 1989
International
Member of the International Astronomical Union (IAU) Executive Committee, 1985 - 1991
Member of the General Prize Committee of the Balzan Foundation, 1985 - date
Foreign member of the Norwegian Academy of Science and Letters, 1987 - date
Member of ESO Council, 1988 - 1992 (president 1988 - 1990)
Member of NOT Council, 1989 - 1990 (president 1989 - 1990)
Member of the Council of the European Astronomical Society, 1993 - date