The village of Roseland had its origins in 1849, when a band of recently arrived Dutch families built their homes along the Chicago–Thornton Road. Perched on the ridge west of Lake Calumet between what is now 103rd and 111th Streets, High Prairie, as it was then known, took shape around the Reformed Church, the small truck farms, and the stores located on the road later known as Michigan Avenue. High Prairie prospered, its farms made profitable by Chicago to its north and the stockyards to the west. Its population grew, most often by additional Dutch settlers who, after 1852, arrived from the east at the Michigan Central Railroad station in nearby Kensington.

After 35 years, the endowment that supported "Pullman Tech," as it was called, could no longer sustain the rising costs of the school's operation as it grew to a student enrollment of 600. Pullman Tech had always educated the children of the residents of the Roseland community. By George Pullman's will, the school was prohibited from charging tuition.  Also, by this time vocational training had increasingly become part of the offerings of the Chicago public school system.  In the late 1940's, after careful consideration of the options, the Board decided that the only practicable means of carrying out Pullman's intention was to close the school and create an educational foundation.  Such a step required approval by the Superior Court of Cook County, which granted the request.

Enter Mendel Catholic High School in 1951.  At the invitation of Samuel Cardinal Stritch, the Augustinian Order opened Mendel Catholic Prep High School in September 1951. The original building and 40-acre campus located at 250 East 111th Street, Chicago had been the site of the Pullman Free School, named for George Mortimer Pullman who was an American inventor and industrialist. He is known as the inventor of the Pullman Sleeping car.

Cardinal Stritch saw the opportunity for a high school that was needed for the Catholic young men in the Roseland community on the far south side of Chicago. In 1950, the Augustinian Provincial, Father Clement C. McHale, O.S.A., was invited to purchase the property with substantial financial help from Cardinal Stritch. Extensive renovation was required before the school could be opened under the leadership of Father John L. Seary, O.S.A. and eight Augustinian priests.

The new school was named "Mendel" in honor of an Augustinian monk, Gregor Mendel, O.S.A., the father of Genetics, whose laws of heredity are world famous, and world-renowned.

New housing development on Roseland's vacant edges brought a short-lived growth spurt in the 1950s and early 1960s. Changing industrial patterns, however, led to a decline in the community's economic fortunes. Production at Pullman and other local industries slowed. As jobs disappeared, workers followed their jobs to the suburbs. Joining them there were residents who feared integration. Despite sporadic efforts to create an integrated community and the commitment of several European ethnic communities to stay in place, the racial composition of the community area changed dramatically between 1965 and 1975. Its economic geography changed even more dramatically as evidenced by the following graph:  

The inflation of the 1970s followed by the collapse of the steel and automotive industries in the 1980s left many of Roseland's newest families without jobs. The virtually complete turnover of population meant that community institutions that had helped residents in earlier times no longer existed or were not established enough to carry the burden. As African Americans moved to Roseland, the dramatic change in the neighborhood's make-up occurred in the Roseland Community as evidenced by the Racial Population in the above mentioned graph. Mendel which average 1,500 students since the early 70’s saw its student population go from 1,200 young men in 1974-1975 to just under 500 students in the fall of 1975. This drop not only affected the financial resources of Mendel, but also literally destroyed its sports teams. Mendel, a regular winner of South Side Championships in football, wrestling, and other sports prior to 1975 had to field teams where African American kids had no prior experience in wrestling, football or the other intercollegiate sports. Mendel lost its prominence in sports as the Roseland area went from white to black. The white residents of Roseland left for the suburbs as the industrial base left the Roseland area. By the mid-1980s, Roseland had become known for its high rates of HUD repossessions and was designated an Urban Homestead area.  Roseland has only started to recover from the effects of those decades of economic decline.

However, the Augustinian order that operated Mendel didn’t give up on the school. The many successes listed below in the athletic portion helps to explain why.