J.L.
I am reading a great book on this exact problem. I have a 5 year old with the same temperament, and trust me, it only gets worse. The book is "Setting Limits with your Strong-Willed Child" I'm half way through and it's already working. I used to spend all my time with warnings, second chances, arguing, bribery, threatenings, until I finally just lost it and started screaming and throwing him into his room. This book is teaching me how to cut all that out and move from a clear message, to an action step right away. These types of kids need very clear boundaries and have to know the bottom line right away. Their whole goal in life is to test you, so you have to be firm and strong without getting angry and engaging him in a power struggle. My daughter is not nearly so trying. She has occasional outbursts, but for the most part wants to do what's right, so not every child is like your son, and he's completely normal. (although I've often thought my son had the devil in him, too) :) I got the book off of amazon. Good Luck!