St. Gregory started out with a school as the foundation. In June of 1958 property was purchased for the school and as a surprise, Fr. Victor C. Côté came with news from Bishop John C. Cody that he had been appointed as pastor of the new St. Gregory’s parish and construction for a Church has been approved. A Church was not anticipated for a few years after the school was constructed, but this was good news. Within two weeks construction started on the school and a month later construction for the Church began.
 
 On December 7th, 1958, the first mass was celebrated at St. Gregory’s, it took just 5 months to build the new Church. The first mass almost didn’t happen on that day, the alter stone was missing but was found locked up in a secure location to keep it protected at Lakewood.
 
 On April 29th, 2006, St. Gregory the Great was to join with St. William and form a new parish and eventually close the doors to the Church.
 
 At its establishment, St. Gregory parish totaled 200 families. By 1959, the parish had grown to 425 families and Basilian Fathers from Assumption University came to assist at Sunday Masses.
 
 Priests at St. Gregory the Great:

Fr. Victor C. Cote 1958-1967
 Fr. Laurent Paquette 1967-1970
 Fr. Laurent Poisson 1970-1974
 Fr. Raymond Fortin 1974-1989
 Fr. Stanley Nouvion (Assoc.) 1974-1975
 Fr. Peter Aquilina (Assoc.) 1975-1976
 Fr. Henry Skoczylas (Assoc.) 1977-1978
 Fr. Gary Goyeau (Assoc.) 1979-1983
 Fr. Peter Hayes (Assoc.) 1983-1988
 Fr. Gabriele Del Bianco (Assoc.) 1988-1990
 Fr. Gerald Quenneville 1989-1991
 Fr. Alan Campeau (Assoc.) 1990-1992
 Fr. John Comiskey 1991-1995
 Fr. Thom Blondin (Assoc.) 1992-1996
 Fr. Maurice Charbonneau (Assoc.) 1996-1998
 Fr. Patrick Fuerth 1995-2004
 Fr. John Duarte (Assoc.) 1999-2000
 Fr. Jan Pochwala (Assoc.) 2000-2002
 Fr. Tom Janisse (Assoc.) 2002-2006
 Fr. Gerard Dewan (Administrator) 2004-2005
 Fr. Gary Goyeau 2004-2017 (Pastor at both sites since 2008)
 Fr. Daniel Bombardier (Assoc.) 2006-2008
 Fr. Chris Gevaert (Assoc.) both sites 2008-2010
 Fr. David Butler (Assoc.) both sites 2010-2012
 Fr. Henryk (Matthias) Chibowski (Assoc.) both sites 2012-2013
 Fr. Antony Kolenchery (Assoc.) both sites 2013-2015
 Fr. Chris Bourdeau (Parochial Vicar) both sites 2015-2017
 Fr. Donatien Lwiyando, S.X. (Parochial Vicar) 2017
 Fr. Al Williams - Pastor Emeritus - Born into Eternal Life October 24, 2018

St. William Parish became a reality with the need of a school.  The families of Emeryville did not want their children bused to Belle River.  In July 1950, the Ellwood family donated 5 acres of land to the Bishop of London.  Later that same month, an additional 5 acres were purchased for a school.  Construction on a 3-room school house was started in November of 1950.  In the fall of 1952, a fourth room was added to the school to accommodate the ever increasing enrollment.  On October 1st, the recitation of the Rosary was held in the school each evening.  The people kept coming in ever increasing numbers.  This practice of daily recitation of the Rosary continued for about a year and a half.  In answer to their prayers, the Bishop announced the formation of a new parish.  The parish was to be called St. William in honour of St. William Abot, who died on January 10, 1209 and was canonized the following year by Pope Honorius III.

On Sunday, July 9, 1955, Mass was celebrated for the first time in St. William Parish.  Mass was held in the school which barely held all the faithful attending.  December 8, 1956 was also an important date for the parish:  at 3:00 pm, "The Stations of the Cross" were blessed by Msgr. C. Pitre and, at 8:00 pm the same evening, the Church was blessed by His Excellency Bishop Cody.  St. William Church was official and Emeryville had its church. 

In 1963, St. William Cemetery was first established, and the first burial took place in 1964.

Priests at St. William Parish:

Fr. Felix Bezaire (Pastor) 1955-1956
Fr. Leo Charron (Pastor) 1956-1959
Fr. Paul Charbonneau (Pastor) 1959-1965
Fr. J. M. Fogarty (Pastor) 1965-1966
Fr. Frederick Doll (Pastor) 1966-1970
Fr. W. Bonnici (Pastor) 1970-1972
Fr. V. Shields (Assoc.) 1970-1971
Fr. A. Aquilina (Assoc.) 1971-1974
Fr. J. Henry Cassano (Pastor) 1973-1976
Fr. A. Camillen (Assoc.) 1974-1975
Fr. J. Barbara (Assoc.) 1975; (Pastor) 1976-1987
Fr. G. F. Scerri (Assoc.) 1981-1987; (Pastor) 1987-1991
Fr. E. Aguis (Pastor) 1991
Fr. R. T. Buchanan (Pastor) 1991-1995
Fr. R. Buchanan Jr. (Pastor) 1995
Fr. Raymond Masse (Pastor) 1995-2001
Fr. Edward Bellefeuille (Assoc.) 1998-2000
Fr. Jim Chaseley (Pastor) 2001-2008
Fr. Gary Goyeau (Pastor at both sites since 2008 - 2017)
Fr. Chris Gevaert (Assoc.) both sites 2008-2010
Fr. David Butler (Assoc.)  both sites 2010-2012
Fr. Henryk (Matthias) Chibowski (Assoc.) both sites 2012-2013
Fr. Antony Kolenchery (Assoc.) both sites 2013-2015
Fr. Chris Bourdeau (Parochial Vicar) both sites 2015-2017
Fr. Donatien Lwiyando, S.X. (Parochial Vicar) 2017
Fr. Al Williams - Pastor Emeritus - Born into Eternal Life October 24, 2018