K.P.
My 2 1/2 year old son is recently in a big boy bed as well. The first few nights we had to do the Supernanny technique. It was absolutely exhausting, but it definitely worked! After he got used to staying in bed, we had the separate issue of him waking up 2-3 times a night and crying for us. After 2 weeks of sleep deprivation (there's nothing like getting a full night's sleep!), I decided to try a sticker chart. I thought he might be a bit too young, but thought it was worth a shot. It's working amazingly well! I took a picture of him "sleeping" and a picture of him "crying" so there would be a visual for him. We showed him that if he sleeps all through the night with no crying at all, that he would get 2 stickers. If he wakes up once, he'll get one sticker and two or more wake ups gets no stickers. We told him that after he gets 5 stickers, that we'll take him to Chuck E Cheese. Both mornings that he's woken up so far he has said, "I was a big boy, I woke up and closed my eyes and went back to sleep!" I hope this helps :) Good luck!