Once you are accepted by the faculty and the University, your application is sent to the College. On the application there is a section in which you can list - preferentially - a number of different colleges. Your accepted application is then circulated to your top-choice first, and they either accept your application, or it is passed onto the next college on the list.
To obtain an application and for more information on the application process, visit Oxford University's application homepage.
Many of the post-graduates at Pembroke are here on merit-based scholarships and bursaries. If you want to learn more about the scholarships available, ask the graduate secretary and visit Oxford University's funding homepage.
Good Luck!
