@Tommy. I do agree that one should never celebrate until the check is in your hand (in this case, the acceptance letter), but given the previous history of the link, I'm still going to wish you an early congratulations Tommy

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@Witt: I have several friends who are or were USC MFA grads and have spoken with them at length about their application process. The majority of them were rejected on their first attempt, though some got in on their first try. I personally don't think that they're trying to test people's commitment, but for this school, persistence can pay off.
We were also told by the Vice Dean that USC's selection is based by cohort, meaning that they want each class to be as diverse as possible. So if you happen to be the only person with the background of say, being a cowboy, among the group that year, then you have a good chance of standing out in the admissions director's mind. But if it just so happens that you're part of a year where there are thirty cowboys applying, then your chances are much slimmer, but only for that year.
Something else that I've gleaned from students and words mention by the Vice Dean, was the USC is really looking for fresh perspectives on film. My friends there have told me that a large portion of MFA acceptees come from very different backgrounds and the ones that DO have a strong film background, sometimes are frustrated with why they are there. Your entire first year will be spent making one silent 5-minute short film on an Sony EX1/EX3, then a 10 minute short film using the same cameras. For people who have a lot of experience, this can be a little frustrating.
My guess is that at the end of the day, USC professors want students that they can mold and shape and not have to fight tooth and nail against during their 3 years at the school there. Like it or not, Hollywood and the film world can consist of a lot of big, passionate egos. USC has also recently come under fire of becoming a school that has too much style over substance and so trying to hammer home "Story is the King" while students are focused on visuals and aesthetics could be difficult. All that being said, there is a chance that USC passes over people because they feel they're already ready to go out into the working world of film. The Vice Dean himself mentioned this when a USC BFA grad asked if their chances were better or worse to apply to the MFA. The Vice Dean responded with, chances are the same, but we'd probably wonder why you're not using your BFA to get job in the field. I think he then looked around to room trying to find a poster of Jon Chu

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For everyone applying for the first time, if you unfortunately don't make it into USC this round, USC will automatically want you to re-apply for the next semester (Spring '12) and will waive you application fee. You'll probably be getting an email about this 1-2 months before the Spring '12 deadline. You will be given a choice of either re-submitting the same materials or requesting to add new materials to re-submit.
Something else to think about for Spring: the numbers are all over the map, but traditionally there are 600-900 applicants for Fall and only 200-300 applicants for Spring, but 60 slots for both. I'd wager that about 15 of those Spring slots are taken by Fall waitlisters (as happened in the year I waitlisted for Spring), meaning 45 open spots for Spring. So chances of Fall acceptance: 8-12%. Chances of Spring acceptance: 15-22%.
Aaaand, I've rambled on long enough ...