 He had three sisters and attended Lisgar Collegiate in Ottawa followed by Yeshiva College where he was valedictorian of the 1935 class and received his rabbinical degree in 1936.As a young Canadian student, Petegorsky studied for a doctoral degree at London School of Economics under Harold Laski.His book "Left-Wing Democracy in the English Civil War" was published as part of the Left Book Club series by Victor Gollancz, and republished by Sandpiper in 1999.