DiCarlo was born in Brooklyn, New York on March 11, 1928, and raised in the Bay Ridge neighborhood. He was educated at St. John's College, receiving a Bachelor of Arts degree in 1950. He then attended the St. John's University School of Law, graduating with a Bachelor of Laws in 1953. He was admitted to the bar in 1954. He completed his education at the New York University School of Law, receiving a Master of Laws in 1957.
