Bishop McElroy attended Saint Patrick Seminary in Menlo Park, California and was ordained a priest of the Archdiocese in 1980. His first assignment was Saint Cecilia Parish in San Francisco, which was the parish where both of his parents had grown up and attended grammar school, and the church where they were married.

In 1989 Bishop McElroy served as a parochial vicar at Saint Pius Parish in Redwood City. In 1995 Archbishop Quinn appointed him vicar general of the Archdiocese. Bishop McElroy was appointed auxiliary bishop of San Francisco by Pope Benedict XVI in 2010 and was ordained by Archbishop George Niederauer at Saint Mary’s Cathedral later that same year. He became the Archdiocesan Vicar for Parish Life and Development and served in that role until his appointment to be the next Bishop of San Diego in 2015.

Bishop McElroy is the President of the California Catholic Conference and serves as a member of the USCCB committee on domestic justice and committee on international affairs.

Bishop McElroy has written two books: The Search for an American Public Theology and Morality and American Foreign Policy. In addition, he has written a series of articles in America magazine touching upon key elements of Catholic social teaching.