We've had this problem with our toddler, too. We were fine with him in our bed, until we had the newbie, and then we did a routine that has worked, even though we have to redo it every few months when his routine gets off. When he comes to our room, we just get up, walk him back to his room and put him back in bed. No engagement, no eye contact, etc. As long as there's nothing wrong with him, and his needs are met, of course. The very first time we did it, DH took him back at least 30 times in a row, and he would just keep coming back, but he finally got tired of the game and went back to sleep. It didn't upset him one bit!
Also, if he's climbing out of his crib, I would definitely look into getting him into a bed, as he can hurt himself falling from that height.
Mama to H (6) B (3) : A (1)