Falk has served since 2018 as President of the Alfred P. Sloan Foundation, which makes grants to support research in the sciences and social sciences, the health of the higher education ecosystem, and the public understanding of science and technology. He served previously as President of Williams College and before that as the James B. Knapp Dean of the Zanvyl Krieger School of Arts and Sciences at the Johns Hopkins University, where he was a professor of physics prior to moving into administrative leadership roles.