In the summer of 1728, Fr. Armand De La Richardie, S.J., came from Quebec to establish “The Mission of Our Lady of the Assumption among the Hurons of Detroit.” In 1765 the sixty some French families living on the south shore of the Detroit River petitioned for a parish of their own. Instead of erecting a second religious centre in the same locality, it was decided that the Mission of the Assumption among the Hurons should become the Parish of Our Lady of the Assumption with the care of the souls of both the Hurons and the French settlers. This integrating development was canonically effected on October 3rd, 1767, when Fr. Pierre Potier, S.J., became the first pastor. That makes Assumption the oldest continuous parish in the present province of Ontario.
A new church building, opened in 1787, was built of timbers (squared logs) and was situated on the eastern edge of the park between University Avenue and Riverside Drive. On July 20th, 1845 that was replaced with the larger Assumption Church building that forms the nave of the present edifice.
In 1870 the Basilian Fathers of Toronto were invited to take charge of the parish and also of Assumption College which had been opened in 1857 by the Jesuit Fathers.
Through all these years the pastoral life of the Church in Windsor thrived. As the population grew, so did the need to divide Assumption Parish. On Pentecost Sunday 1917 the Parish of Our Lady of Prompt Succour was carved out of Assumption. (This parish and its church were later renamed Holy Name of Mary.) At the west end of Assumption Parish the mission chapel of The Blessed Sacrament was established in 1937. In 1956 Holy Name of Mary Parish was divided and St. Patrick’s Church was established. It was served by the Missionaries of St. Charles (Scalabrinians).
Population shifts and declining numbers of priests led to the reunification of Assumption Parish in recent years. For over two and a half centuries, God has been glorified through worship and service of neighbour in southwestern Ontario in Our Lady of the Assumption Catholic Parish.