I agree with what racccjlm said about not covering material in your application, but with a couple caveats: First, schools do 'closed book' or 'open book' interviews. In a 'closed book', the interviewers won't have looked over your application, so there's no harm covering that ground again if it's useful. Research your particular school to find out how they do it. I just plain outright asked at the beginning of my interview - don't be shy about doing that. It's not a state secret. I tried to be tactful about how I asked - something like "So I don't cover ground you've already read about, can you tell me if you've reviewed my application?" Second, having SOME overlap with your application is good, because it promotes the image of a coherent, unified application where the strong points are repeatedly emphasized. There's a balance between over-repetition and leaving them wondering why you didn't include something on your PS or whatever.