Terryville's Catholic history dates back to the mid 1800's when the Ryan family moved to Terryville from Thomaston.  Rev. Michael O'Neill traveled from Waterbury once a month to celebrate mass in the Ryan house.  As attendance increased, schools were used for the monthly Masses.  The little mission church of the Immaculate Conception was at various times affiliated with Immaculate Conception of Waterbury, St. Joseph Church in Bristol, and finally St. Thomas in Thomaston.  It eventually became apparent that the parishoners needed their own church to worship in.

In 1881, John McNamara and Thomas Burns along with Rev. Eugene Gaffney presented a formal petition to Bishop Lawrence McMahon of the Diocese of Hartford.  The church was incorporated on December 14, 1881.   Land was purchased in January, 1882. Construction soon began, and was completed in the same year under the supervision of Rev. Gaffney.  Following Father Gaffney at St. Thomas was Reverend Michael McGivney (founder of the Knights of Columbus), and Reverend M. J. Daly.

Parishoners petitioned Bishop Michael Tierney in 1899 to become a full parish.  The petition was eventually accepted on April 16, 1900.  The Immaculate Conception at long last became an official parish in the Diocese of Hartford.

Full-time Pastors from 1900 to Present are as follows:  Reverends John J. Neale, John H. Sheehan, James A. Broderick, Wiliam A. Gildea, Joseph A. Degnan, Edwin A. Flynn, John J. Delaney, Francis J, Mihalek, Walter T. Hines, Thomas J. Ritucci, Edward V. Muha, and Gerald H. Dziedzic.

As part of our centenial celebration in 2000, Cecile Dechaine documented and published the history of the church "1900 - 2000  A Century of Change at the Immaculate Conception Church."  The details listed above, as well as many other details, can be found in this book.  Contact the rectory if you are interested in obtaining a copy.