Originally invited by Victor Weisskopf to lead the Theory Division in 1961, he twice served as Director of the Theoretical Physics Department (1966-1968 and, on a part-time basis, 1972-1974).

In 1976 the two CERN Laboratories (Prévessin and Meyrin) were formally amalgamated, with John Adams as Executive Director-General, responsible for the administration of CERN and the construction of machines and buildings , and Léon Van Hove responsible for the research activities of the Organisation.

His mandate as Director-General for Research (January 1976 - December 1980) saw the preliminary proposal for the LEP Collider, with ideas for its experimental programming, which his successor, Herwig Schopper was to see cons tructed.

From 1975-1980 he was a member of the Pauli Committee and was Chairman from 1980 until his death in 1990. He chaired the Ad-Hoc Archive Committee, which established today's Archive Committee.