Joseph J. Greenbaum was born February 23, 1924, in the Bronx. He served in the United States Army during the Second World War, and later attended City College as the first member of his family to receive a college education. After earning his Bachelor of Social Sciences degree in 1946, Greenbaum pursued a PhD in Psychology at the University of California, Berkeley, where he was mentored by Edward Chace Tolman. He was awarded a doctorate in 1950.

From 1950 until June 1957, Greenbaum taught at Wesleyan University in Connecticut as an assistant professor. His specialty was experimental psychology, a concentration that he brought to The New School when he joined the Graduate Faculty (now, the New School for Social Research) as an associate professor in 1957. In 1962, he was promoted to full professor.

Greenbaum served as the chair of the Psychology Department from 1959 until 1963. After brief service as vice dean of the Graduate Faculty from 1964 to 1966, he became dean of the Graduate Faculty from the 1966-1967 academic year through the 1978-1979 academic year. Greenbaum then returned to the Graduate Faculty Psychology Department, where he taught until his retirement in 2003; his New School career lasted more than forty years. Among his courses were Statistics, Processes of Learning, Basic Problems in Psychology, Culture and Personality, Methods of Social Psychology, Cognitive and Modern Theories of Psychology, and History and Systems of Psychology.

For his work with the Federal Republic of Germany to establish the Theodor Heuss Chair at the Graduate Faculty, which brought German scholars to the United States, the West German government awarded Greenbaum the Officer’s Cross of the Order of Merit in 1972. In 1990, The New School honored him with a Distinguished Teaching Award. Joseph Greenbaum died on May 3, 2011 in Berkeley, California.