My 21 month old did the same thing. First he learned how to jump out of his pack n'play, where he slept when we were at Grandma's. Then only a couple days later we found him perched on the railing of his crib, calling out to us to see what he had done, he was so proud of himself! We knew it would be rough on us, but we decided rather than letting him fall we would transition to the big boy bed. We really wish he could have stayed in his crib longer, (like all our friends with kids that age!), but I knew I wouldn't sleep at night wondering if he was about to crawl/fall out. For about a month he got out of bed as soon as we left the room, and he cried and tried appealing to us in all the ways he knew how. I will say that he did learn to stay in bed even though it felt like ages, we had a great bed time routine and consistently put him back in. When he realized crying wouldn't get him anywhere, he would get out of bed with both his stuffed animals, go to his door, lay down, and fall asleep, every night without making a peep. Some cute pictures came out of that one! We have a stubborn one so it was tough, but I think no matter what age you transition to a toddler bed you will have the same issues. We just had to resolve ours sooner than our friends. Good luck!