a great deal since I took it a hundred years ago. The State site is probably the best source of information. If there are any recent-select FSOs here, they can give specifics.

Back in the day, the written portion was an excuse to play Trivial Pursuit (r) with yourself, even if there was no hope or intent of passing. Full disclosure -- I was seriously considering leaving the military for the diplomatic corps, where my mother's side of the family was well established. AND, BOY, AM I GLAD I DIDN"T!!!! After service on four country teams, it became obvious to me that I was able to do all the diplomatic stuff the suits did, but I got to have all the fun that they didn't. And a couple of moments of unscheduled excitement.

As I understand it, the written test is still used as a "select out" process, while the interview portions are the "select in".