Originally Posted by Academic

There are lots of threads on this, but the process is simple and fast. You can have your bags checked all the way through, so you don't need to go through Customs or leave airside. From your PHL flight, keep a lookout for the immigration booth on the left, immediately before the escalators going down to Customs. There's a simple passport check, then you continue on to the International part of the terminal along a long moving walkway. Depending on your arrival gate this can all be done in less than 15 mins.