Carl Kaysen, who served as the Institute for Advanced Study’s fourth Director from 1966 to 1976, overseeing a decade of growth and change, died on February 8 at the age of 89. A political economist with a distinguished career in public service, he was President Kennedy’s Deputy Special Assistant for National Security Affairs from 1961 to 1963, and was most recently the David W. Skinner Professor of Political Economy, Emeritus, at the Massachusetts Institute of Technology in Cambridge, MA.