Marc Kamionkowski is a theoretical physicist who specializes in cosmology. He earned a B.A. in physics (1987) at Washington University in St. Louis and a Ph.D. (1991) in physics at the University of Chicago, followed by postdoctoral study at the Institute for Advanced Study in Princeton (1991–1994) and a junior-faculty position at Columbia University (1994–1999). From 1999 to 2006 he was Professor, and from 2006 to 2011, the Robinson Professor, of Theoretical Physics and Astrophysics at the California Institute of Technology. In 2011 he joined the faculty at Johns Hopkins University as Professor of Physics and Astronomy.