To date, Bishop Mulhall’s service to the Catholic Church has been rooted in two locations — his home diocese of Peterborough, and Rome.

Following his ordination to the priesthood for the Diocese of Peterborough in 1989, Bishop Mulhall returned to Rome to further pursue his religious studies at the Augustinianum while following the formation program at the North American College.

In obtaining his Licentiate of Sacred Theology (S.T.L.) there, Bishop Mulhall embarked on a two-year program that provides opportunity to treat theological questions in greater depth and pursue a more scientific study of theology. Graduates of the program are prepared to teach theology in a college, seminary or university, or to function as a chaplain to various professional groups, or to act as a theological resource for a diocese.

Bishop Mulhall returned to the Peterborough Diocese in 1991 and served as a priest in Huntsville until 1994.

He made a third move to Rome in 1994, to serve as an official of the Holy See in the Congregation for Oriental Churches. Established by Pope Benedict XV in 1917, the mandate is to be in contact with the Oriental Catholic churches for the sake of assisting their development, protecting their rights and maintaining the heritage of the various Oriental Christian traditions. Its role includes exclusive authority over such regions as: Egypt and the Sinai peninsula, Cyprus, Greece, Iran, Iraq, Lebanon, Palestine, Syria, Jordan and Turkey. The responsibilities reflect the complex reality of the Oriental churches with respect to their geographical, cultural and social conditions.

In 2002, Bishop Mulhall returned to his native diocese, serving again briefly in Huntsville and then in Hastings.

A year later, he was given added responsibilities as chancellor for spiritual affairs and in 2004 he took on the duties of vicar general of the diocese. He occupied these positions until June 30 of this year, when he was appointed Bishop of Pembroke by Pope Benedict XVI.