Sean Mac Cartain is a native of Co. Offaly who qualified as a Rural Science teacher on a Department of Education course in Cork in 1955. He did the TTG course in 1959 qualifying as a teacher of Irish. He did a BA from UCD in 1965 and an HDipEd from Maynooth in 1967. In 1972 he was conferred with his MEd from Trinity College Dublin
Sean Mac Cartain taught in Gort, Co. Galway, and Cootehill Co. Cavan before becoming Principal of Virginia Vocational School in 1962. He also served as principal in Cavan Vocational School, and from 1971 to 1980 he was Principal of Naas Vocational School, Co Kildare. In 1980 he became the Chief Executive Officer of the Co. Offaly Vocarional Education Committee, retiring in 1995.
He is married to Maire Ni Choisdealbha of Athlone, and they have a family of four, Catriona, Poisin, Eoin and Micheal. He has published widely on educational and other matters.