[2] After two years at the minor seminary, Deeley received the Basselin Foundation Scholarship, allowing him to attend the Catholic University of America in Washington, D.C. After graduating in 1968 with a Bachelor of Philosophy degree, he entered the Pontifical North American College in Rome, earning a Bachelor of Sacred Theology degree at the Pontifical Gregorian University in 1972.

[2] On July 14, 1973, Deeley was ordained a priest for the Archdiocese of Boston by Cardinal Humberto Medeiros at Sacred Heart Church in Watertown, Massachusetts.

[2][1] Following his ordination in 1973, the archdiocese assigned Deeley to serve as an associate pastor at St. Bartholomew Parish in Needham, Massachusetts.

Deeley returned to Boston in 2010 when Cardinal Seán Patrick O'Malley named him vicar general and moderator of the curia.

[1] Deeley chose "Veritatem facere in caritate" ("Living the truth in love") from St. Paul's Letter to the Ephesians as his episcopal motto.

[4][1] On September 16, 2016, a Maine man sued Deeley, claiming that he had been sexually abused as a child by two diocese priests.