On May 21, 1911, Bishop James Trobec granted approval to approximately 35 families to build a Catholic Church in Rockville. Dinners, bazaars, and raffles were held to raise money to build the church. Rev. Hubert Gunderman, the pastor of Luxemburg, provided spiritual guidance for the new church and it was incorporated as Mary of the Immaculate Conception. The 48x84 foot church, which cost $10,872 was built on land that was donated. Looking to the future, the church was built to hold 325 adults with room for 100 more in the choir loft. Much of the labor was provided by parishioners and friends. Everyone helped to build the church which became a community project.
The cornerstone was designed from a huge boulder from the basement excavation. The cornerstone was blessed and laid on September 9, 1911, by Father Hubert Gunderman, pastor of St. Wendelin in Luxemburg. Today the cornerstone is framed in the north side wall of the narthex.
Father Gunderman arrived by a cutter from Luxemburg to celebrate the first Mass on December 8, 1911, the Patroness’ Feast of the Immaculate Conception. Fr. Julius Lochnikar, OSB, was the first pastor in Rockville, serving from 1912–1921.
In 1991, a Parish Center was built and the church basement was converted into the religious education center for faith formation classes.
In 2004, the narthex addition was added to the front of the church.