After Carter lost the 1980 election to Ronald Reagan, Lake became the Five College Professor of International Relations chair in Massachusetts (1981–1992), teaching first at Amherst College. In 1984, he moved to Mount Holyoke College, where he taught courses on the Vietnam War, Third World revolutions, and American foreign policy. (He left Mount Holyoke College in 1993 to become National Security Advisor from 1993 to 1997.) Among his protegees at Mount Holyoke was his student research assistant Mona Sutphen who would later serve in the Barack Obama White House as Deputy Chief of Staff for Policy. In 1997, he became Distinguished Professor in the Practice of Diplomacy at Georgetown University, until accepting his position with UNICEF.