How can I get my 5 month old baby to sleep in his crib?

Since he was 3 months, he's waken up more an more in his crib (every 1-2 hours). Lately, we've resorted to having him in bed with us. He falls asleep easily when beside us but never on his own without being rocked. Also, for those of you who will say that it's okay to have him in bed with us - when do children usually grow out of this?