After graduating from high school in 1951, Mazur began work in the Health and Welfare Department of New York City's dressmaker's Local 22. In 1955, Mazur entered the ILGWU's Training Institute, a 1-year intensive program to prepare students for staff appointments in the ILGWU, and was assigned as an organizer in the Upper South Department and the New England Region. After graduation in 1956, Mazur was assigned to Local 40, where he became Director of Organization and Education. In 1959, Mazur began working for Local 23, which later merged with Local 25 to become Local 23-25. Mazur began work as an organizer for the local in 1959, was elected as Assistant Manager in 1964, and manager in 1973.
