Born in Alberta and raised in Winnipeg, Cohen graduated from the University of Manitoba where he wrote for the Manitoban and other student publications. After completing a degree in Social Work in Toronto, he worked there and in Montreal as a social worker, writing in his spare time. In 1956 his wife, Dian Nusgart, encouraged him to turn to writing full time. Within the first two years he sold over fifty scripts, set-up a theatre company with two others, and wrote a regular column on theatrical activities for the Montrealer. In 1960 he received a Canada Council Grant for the study of drama in New York and London. Initially Cohen wrote mainly half-hour dramas for radio and television. He wrote a series of plays dealing with Canadian history, numerous scripts for the National Film Board, and several other productions. His first major success was the film-play Dry Landers produced by the National Film Board. His flair for historical drama led him to modest acclaim in Canada and to a much wider audience south of the border. Many of his television screenplays were aired on American television in the 1960s, 1970s and 1980s; the best known was Roots.