Barbara Gilson was born in Lexington, Massachusetts on February 8, 1925 to Royal Gilson, a bank examiner, and Ruth Caddell Gilson. She attended Lexington High School and entered Mount Holyoke College in 1942. She received her B.A. in 1945 with a major in history. She was one of the members of the Class of 1946 who accelerated her course of study to graduate a year early. She attended Radcliffe Secretarial School in 1953. She worked for the Boston Public Library from 1942-1953, as a secretary at Standish, Ayer & Myer, Inc. in Boston from 1953-1954 and at Vectron, Inc. in Waltham, Massachusetts from 1954-1955, and as an administrative assistant for The Terrell Corporation in Wilmington, Massachusetts from 1955-1965. She then worked as administrative secretary for Symmes Hospital in Arlington, Massachusetts. In 1969 she was working as executive secretary at Waltham Hospital (Waltham, Massachusetts).