Baby crawling out of the crib?

Mines just started doing that. I had to lay him down 5 times today before he finally fell asleep for nap time!!! Luckily we have a convertible crib... guess it's time to put the toddler bed side on. I don't want him falling out on his head.
Anyone else dealing with this right now? How do you get them to stay in bed at night and for naptime? I think we're going to have issues... ;)
~Amanda