The school is named for Rita of Cascia (1381–1457), an Italian Augustinian nun and Roman Catholic saint.

The school was formally dedicated on 22 April 1906, at which time the San Francisco earthquake of four days earlier was invoked.

In January 1935, a fire caused extensive damage to the school's shrine after an altar candle was placed too close to a Christmas tree.

This period also saw the construction of the Mendel Technical Building (1938), and an addition to Egan Hall (1939), which (at the time) made St. Rita the largest all-boys Catholic school in the American Midwest.

[22][23] A fire destroyed the wooden stands in the athletic stadium in 1944, and were soon replaced with concrete bleachers.

[19] An April 1939 benefit for the addition included actors Arthur Treacher, Fifi d'Orsay, Eddie Bracken, and Virginia Payne.

[25] The Archdiocese of Chicago closed Quigley South prior to St. Rita's purchase of the property, returning the Chicago minor seminary to its original site at Archbishop Quigley Preparatory Seminary.

Father Thomas McCarthy, O.S.A., continued to serve as both the chairman and the chaplain of the school; he also focused on his new position for the Augustinian Order's new Director of Vocations.

[30] Students are placed into one of three academic programs, based on an entrance exam score, and input from parents and previous teachers.

[31] As a part of the Augustinian Academy program, the school offers 12 Advanced Placement courses: 2-D Design, Studio Drawing, Calculus, Chemistry, English, Latin, Music Theory, Psychology, Spanish, U.S. History, World History.

[31] The school sponsors 14 extracurricular activities ranging from academic competition and publishing to student government, and performing arts.

[44] In 1955, St. Rita of Cascia High School partnered with the Experimental Aircraft Association (EAA) to become the founding High School of EAA's Project Schoolflight, a nationwide youth outreach program.

[45] At that time, St. Rita had the top Aviation Industrial Arts Program at the High School level in the USA.

[47] Blacker helped the students of St. Rita form the first Junior Chapter in EAA history[48] and he also wrote articles in the EAA's Sport Aviation magazine which included photos and stories of St. Rita High School students working on the aircraft.

[49][50][51] A St. Rita student's real life story of his two years in Blacker's Aviation classes is in the external link below entitled: "From a Baby Ace to a Ford Tri Motor".

Blacker's 1958 book, Basic Aeronautical Science and Principles of Flight, has an 'In Appreciation' Forward section on page v. which extends "deep gratitude" to The Reverend Coyne.