Immaculate Conception School was founded in 1887 under the direction of Rev. Matthew O'Keefe, pastor the Church of the Immaculate Conception.  In September of 1887, the school's first fifteen pupils held classes in the church basement and by the end of the year, enrollment had reached forty-six. Two Notre Dame sisters were assigned as teachers and Father O'Keefe offered the rectory for their use, moving into a nearby boarding house.  

Fr. O’Keefe bequeathed to the parish the proceeds from the sale of real estate he owned in Towson and Richmond to erect "a first class school house capable of accommodating not less than a thousand children ... proportionately conformable to the style and beauty of the Church" and one lot west of the cemetery. School construction had commenced in 1921, and by November 5, 1922, the school was ready for dedication by the newly appointed Archbishop Michael J. Curley.

Finally opened on September 11 and solemnly dedicated on November 23, 1923, the three-story building of ornamental white hydraulic brick trimmed with Green River limestone was indeed a fine building, "in conformity to the beauty of the church." Internally supported by a steel frame, the school had firewalls separating the main stairway from the body of the building and housed eleven classrooms, science laboratories, rooms for domestic science, music and typing, a library and 700-seat auditorium that doubled as a gymnasium. The school was so large, in fact, that the Sisters of Notre Dame could not supply enough teachers, and on August 18, 1926, the Sisters of Saint Francis of Glen Riddle, Pennsylvania, assumed management in 1983.

Until 1954, Towson Catholic High School was housed in the same building (on the third floor) as the elementary school. 

Today, ICS is home to more than 550 students each day and includes a pre-school program for ages three and four and an elementary and middle school program as well. Many modern changes to the school can be found including a state-of-the-art computer lab, two new science labs, wireless Internet access and projection devices used by teachers of all grade levels.  And while modern changes abound on campus, the same core Catholic values remain the same.