Oakhill College is a Catholic, co-educational, secondary, day school, located in Castle Hill, New South Wales, a suburb in the Hills District of the Greater Western region of Sydney, New South Wales, Australia. Founded in 1936, the College is run by the De La Salle Brothers in the tradition of St. Jean-Baptiste de La Salle, and currently caters for approximately 1,600 students from Years 7 to 12. Oakhill College is a member of the Independent Schools Association (ISA), and is a school of the Diocese of Parramatta. The De La Salle Brothers purchased the Oakhill property in 1932. The school commenced in August 1936 with four students, increasing to 30 in 1937 when there were 10 day and 20 boarding students. The College served the then rural area of "The Hills", and grew slowly until in 1953, its enrolment reached 100. In 1974 the decision was taken to phase out the boarding school and, in 1976 Oakhill College became a co-educational senior school. The phasing out of primary classes commenced in 1980, and by 1983, Oakhill College was enrolling only secondary students. In the year 2006, the 100th year of the Brothers in Australia was celebrated with a mass at St Mary's Cathedral.