Is This Chess Position Illegal?

I find it quite fun to search a chess board to see if a certain position is legal or not. And by legal, I mean it is a something you can find in a normal game. Is this position able to happen in an actual game? In other words, is this position legal or illegal? Post your answer, and tell me what you think the answer is. If illegal, also tell me what is wrong with the position. I'll post the solution when someone answers correctly.