In 1970, he became Professor of Experimental Solid State Physics at the University of Copenhagen, a chair he held until his death. From 1971 to 1976 he also served as Director of the Riso National Laboratory, and from 1986 to 1989 as Director of NORDITA (the Nordic Institute for Theoretical Physics), with its close connections to the Niels Bohr Institute. Mackintosh was also President of the Danish Physical Society from 1976 to 1979, and President of the European Physical Society from 1980 to 1982.