Polish immigrants settled in Terryville in significant numbers in the 1890s. At first they worshiped at Immaculate Conception Church, but in December 1900 the St. Casimir Society, a Polish fraternal organization, was formed and soon purchased land for a Polish Catholic church on Allen Street in Terryville. St. Casimir Church, 17 Allen Street, was dedicated on September 1, 1907. Since 1999 the two parishes of Immaculate Conception and Saint Casimir have been linked.
St. Casimir Church, Terryville (1907)