He studied theology in Rome, and he earned a degree in theology from the "Angelicum". On his return to Canada, he taught Scripture at St Augustine's Seminary from 1960 to 1967. He then studied at the University of Würzburg in Germany and obtained a doctorate in theology there in 1970. He taught exegesis at the Toronto School of Theology from 1970 to 1976, when he was named Auxiliary Bishop of Toronto on 27 May 1976. On 22 May 1986, he became Coadjutor Archbishop of Toronto, and he duly succeeded to the position of Archbishop of Toronto on 17 March 1990.