St. Kilian Parish as it exists today was founded upon the 1999 merger of two congregations: St. Patrick, Erin (1855-1999) and St. Kilian (1863). Mass was first celebrated in Erin Township at William McGrath’s home near Monches.  Those who gathered there were organized as St. John’s Parish in 1843.  Around 1855, northern Erin residents built their own church dedicated to St. Patrick.  Initially it was served by St. John’s pastors.  The first effort at building a Catholic church in Hartford was made about 1858 by two bothers, Simon and Casper Dorn.  They offered to give $400 each toward the project, provided the other twenty-two Catholics in the vicinity would raise $1,000.  They were unable to raise the funds, so the plan did not materialize.  Next A.B. Thornson proposed to give an acre of land under the condition that local Catholics build a church thereon.  After the deed was made to Bishop Henni, the title was discovered to be defective because the railroad company had a mortgage on the land.  Even though the lumber for the building was already on site, the project had to be abandoned.  In 1863, Fr. Michael Deisenreider of St. Lawrence Parish, rural Hartford, organized 100 Catholic families from the city to form St. Kilian Congregation.  Simon Dorn donated the land for that church.  It still stands on the northwest corner of State and Forest Streets.

St. Patrick’s and St. Kilian’s had connections going back to 1868 when St. Patrick’s was made a mission of St. Kilian’s.  This relationship lasted until 1906.  The two parishes connected again from 1941-1971 while Erin Township was again a mission of St. Kilian parish, served by St. Kilian’s assistant pastors and, later, St. Joseph’s Hospital’s resident chaplain.  Besides these connections, there had been traditions of sharing the Catholic school and religious education program. Several of the pioneer families from both parishes have familial ties.  The parish maintains St. Patrick’s Chapel in Erin.