In 1939, he earned a master's degree in organic chemistry from the University of Pennsylvania. In 1939, The American-Scandinavian Foundation awarded Anfinsen a fellowship to develop new methods for analyzing the chemical structure of complex proteins, namely enzymes, at the Carlsberg Laboratory in Copenhagen, Denmark. In 1941, Anfinsen was offered a university fellowship for doctoral study in the Department of Biological Chemistry at Harvard Medical School. There, Anfinsen received his Ph.D. in biochemistry in 1943. In 1979, he converted to Judaism, by undergoing an Orthodox conversion and that same year he quit smoking. Although Anfinsen wrote in 1985 that his feelings on religion still reflect a fifty-year period of orthodox agnosticism.