The Dormition of the Mother of God Byzantine Catholic Church, affectionately referred to as St. Mary's, was organized in 1906 to serve the Greek Catholic immigrants from the Austro-Hungarian empire who had immigrated to the area to serve in the coal mines and brick factories. These men and women began moving to the area from Europe in 1900, when agents for the mines and factories visited their home villages and encouraged them to find "gold in the streets" of the new country.

The Clarence-area Greek Catholics initally attended St. John the Baptist Greek Catholic Church in Hawk Run, organized in 1904. After two years of the arduous weekly sixty-mile round trip, a group of men and women organized a Greek Catholic congregation in Clarence. The parish was placed under the patronage of the Dormition of the Mother of God, since the founding date of the parish was close to the Feast Day of the Dormition (August 29 on the then Julian calendar and August 15 on the Gregorian calendar).

Dormition parish has always been served by the Greek Catholic priest residing in Hawk Run. The parish has a church with a social hall beneath. The parish has never had a separate hall or a rectory.

In 1950, the Bishop of the then Pittsburgh Greek Catholic Exarchate decreed that the use of the identifiying term "Greek Catholic" was to be replaced by the identifiying term "Byzantine Catholic".

Dormition parish celebrated its one hundredth anniversary on Sunday, August 20, 2006. His Grace, Archbishop and Metropolitan Basil M. Schott, OFM celebrated a hierarchial Divine Liturgy at Dormition Church.