Sanders was born in Union City, New Jersey. His father was English-born musician George Harold Sanders, and mother Rose Rachlin was daughter of Russian Jewish immigrants. He had sister Marilyn. The family did not practice any religious traditions, but when in the U.S. Army Sanders filled a form which required to indicate religious affiliation, Sanders chose Judaism.
In 1960 he won a Fulbright Fellowship for research of French socialists and moved to live in Paris for this purpose. He took this opportunity to travel to the Soviet Union and for his first trip to Israel.
Sanders died of liver cancer, aged 58.
Books in order of publication:
- Socialist Thought: A Documentary History, 1964
- Israel: A View from Masada, 1966
- The Downtown Jews: Portrait of an Immigrant Generation, 1969
- Reflections on a Teapot, 1973
- Lost Tribes and Promised Lands; The Origins of American Racism, 1978
- The Lower East Side, 1980
- The Days Grow Short: The Life and Music of Kurt Weill, 1980
- The High Walls of Jerusalem: A History of the Balfour Declaration and the Birth of the British Mandate for Palestine, 1984
- Shores of Refuge: A Hundred Years of Jewish Emigration, 1988
- The Americanization of Isaac Bashevis Singer, 1989