run to a library or bookstore and get "love and logic". he's not too young for time outs, but it has to be done in an effective way. trust me, this is the time where he figures out how to push yoour buttons, get what he wants, get a fun big reaction from you, what kind of attention he can get, etc. i wish i had done it with me second child, who is still very difficult at 5, because it's hard to re-train. we've been very consistant with this method with our 2-yr old since he was 1, and would do the same thing your son is doing, and he is now very obedient. the idea is to allow consequences to occur, instead of punishment. you can provide the conseqence, we use his crib, and just say "oh, too bad!" in a sing-songy voice and put him in his crib for a few minutes. the idea is, no reaction (kids love that big reaction!, but just so he realizes "when I do A, B happens" not that he's in trouble or that he gets negative attention (attentiuon is attention to a child). anyway, it teaches choice and consequence, and the book or tapes explain it really well. good luck!