In September 1963 he took up a position at the newly founded Southwest Center for Advanced Studies, the private research organization that in 1969 became the University of Texas at Dallas, where he was one of the founding faculty members. He was based at UTD for the remainder of his career, eventually becoming professor emeritus. He was visiting scholar at King's College London for the academic year 1961–1962, at the University La Sapienza in Rome for 1968–1969,