The rally comes after reports that the school was facing an uncertain future and that Father Michael Pfleger had been asked to take over.
Leo officials told the crowd that enrollment and test scores are up, and they report that a number of seniors have been accepted at some of the best schools in the Midwest.
On Thursday, the superintendent of catholic schools for the archdiocese thanked Leo's principal for all he has done.
"Leaders are everywhere and we'll accept leaders from everywhere, but right now what's important for Leo is to remember is that it is not only Lion pride but growing in its service to young men in this community and to the world," said Sister Mary Paul McCaughey, Superintendent of Catholic Schools.
As for Pfleger, he says he does not have experience heading a school and wants to remain at St. Sabina where he has been since 1981.