 He returned to the United States in 1989, joining the faculty of the Department of Physics at UCLA.Soon thereafter, he became Chair of the Department, a position he held until becoming Dean of the Division of Physical Sciences of the College of Letters and Sciences in 1993.Until his death in June 2020, Peccei was on the Editorial Board of Nuclear Physics B Supplement, and the Journal of Physics G. He was a member of the Club of Rome, a Trustee of the World Academy of Art and Science and President of the Fondazione Aurelio Peccei and he was a Fellow of both the American Physical Society and the Institute of Physics in the United Kingdom.