This was the hardest of the clep test I have taken. I studied for around 2 months using InstantCert and the Petersons Air Force study guide (it was free and available for everyone until recently). I did pass, but it was by far the hardest of all the cleps I have taken. Make sure and study alot first. I had been out of school for over 20 years, and that could have made a difference in the level of difficulty.