 Baran died prematurely from a heart attack in 1964 and Wolff transferred to Yale University, where he received an MA in economics in 1966, MA in history in 1967, and a PhD in economics in 1969.As a graduate student at Yale, Wolff worked as an instructor.His dissertation, "Economic Aspects of British Colonialism in Kenya, 1895–1930", was eventually published in book form in 1974.