St. Mary’s Church was built in 1863 on York Road near Church Street. It was the first church built in the area. In 1898, fire completely gutted St. Mary’s Church. Instead of rebuilding on the same piece of property, a large plot further south was purchased where it was possible to build not only a church and a rectory, but also a one-room school with living quarters above for the Sisters of St. Agnes (of Fond du Lac, Wisconsin) who had been recruited to teach. Immaculate Conception Grade School opened in 1900 with an enrollment of forty pupils in all eight grades and was staffed by two Sisters and a postulate. Classes were taught in German. In two years, the number of pupils increased so that it was necessary to add two more rooms in the rear of the schoolhouse.
When Father David McDonald became Pastor in 1916, he learned from church records in Chicago that the original title of the parish was Immaculate Conception. The name St. Mary’s had been used because it was more familiar to the early German residents. When the American Bishops dedicated the United States to the patronage of the Immaculate Conception in 1916, the pastor saw this as an opportunity to reinstate the original name of the parish. Father McDonald recognized the need for expansion of the school and bought the present property on the corner of York and Arthur Streets. His successor, Father Patrick J. Hennessy built a school and hall on the corner. It was used as a parish building up until the time it was destroyed by fire in 1946.
The present Immaculate Conception Church and Grade School was built next to the hall on Arthur Street in 1929. Father John Foley (1924-1932) thought it best to build a combined church and school building. Immaculate Conception Church is located on the ground floor. Eight classrooms were completed on the second floor, with an unfinished third floor. The third floor was completed in 1936 to be used for High School classes until 1953 when the parish was granted a loan from the Diocese of Joliet for the building of a new high school building at 217 Cottage Hill Avenue. In 1957, eight additional classrooms were added to the grade school building. In 1961 a Parish Center was erected on the corner of York and Arthur consisting of a gymnasium, a parish meeting hall and kitchen, several smaller meeting rooms, and an 800 seat worship space named Sacred Heart Chapel.
From 2002 to 2006, renovations to the grade school building included the ground floor pre-school room, third floor art room, and fully equipped junior high science lab, administrative office suite including conference room, faculty workroom/lunchroom, and central air conditioning throughout the building.
Currently, a classroom refresh cycle has been implemented. Classrooms are currently equipped with wireless technology and Smartboards. ICGS has (3) dedicated Preschool classrooms as well as a Math & Science Tech Lab, Art Room, Reading Specialist Room, and Math Specialist Room.
