La Salle College Preparatory was founded in 1956 at the request of the Archbishop of Los Angeles who wanted a Catholic boys high school to serve the northern and eastern sections of the San Gabriel Valley. La Salle College Preparatory continues to function as a private Catholic, co-educational, college preparatory high school. It is a Lasallian School- an educational institution that draws its philosophy and inspiration from the Christian Brothers, whose reputation for excellence in education extends back to the year 1680. The Christian Brothers , assisted by more than 85,000 lay colleagues, teach over 930,000 students in 83 countries. These schools serve nearly every ethnic group and religion around the world. In addition to providing strong academics, each Lasallian school creates a community of persons deeply conscious of their responsibilities to each other, which is central to their success.

La Salle College Preparatory is dedicated to excellent students performance in academics, arts and athletics. Of particular importance is La Salle College Preparatory's call to carry out the Mission established by its founder, Saint John Baptist De La Salle, "to give a human and Christian education to the young, especially the poor." Lancer athletics, Student Life, visual and performing arts, honors and service societies, student clubs and organizations, and student television broadcasts and publications, provide a healthy and warm community atmosphere for all La Salle students.