[1] During his priestly ministry, Harrington served as archdiocesan assistant superintendent of schools and pastor of Holy Name Parish in Birmingham, Michigan.

He was consecrated on January 6, 1994 by Archbishop Adam Maida, with Bishops Dale Melczek and Walter Schoenherr serving as co-consecrators.

[2][1][3] As auxiliary bishop, Harrington served as vicar of the Office of Pastoral Services for Parishes[4] in the archdiocesan curia, episcopal liaison for the Pope John Paul II Cultural Center in Washington, D.C., and regional bishop for Macomb County, Michigan and St. Clair County, Michigan.

On April 15, 2008, Harrington commented on the plans of Kathy Redig, a chaplain in the diocese, to undergo an unauthorized ordination.

The university’s stance is similar to that of Catholic politicians who say that they are pro-life and then support legislation and vote for programs that foster abortion.