Mark Lane was born in The Bronx, New York, the son of Harry Arnold and Elizabeth Levin (Levin was changed to Lane in the 1920s), and raised in Brooklyn, New York. He served in the United States Army after World War II. After attending Long Island University, he received an LL.B from Brooklyn Law School in 1951. As a law student, Lane was the administrative assistant to the National Lawyers Guild and orchestrated a fund-raising event at Town Hall in New York City that featured American folk singer Pete Seeger.