Help your child be excited about the transition. If you can, let him "help" you pick out the bed. We gave my son several options (showed him pictures on the computer) and he picked out his bed. Then he "helped" his dad put it together. Letting him be somewhat in control of this transition helped a lot. As for keeping him in his room, first just tell him it is bedtime and that he needs to stay in his room unless... (there are exceptions, like if there is a fire, or a nightmare, or...). Once you have set the expectation, then if he comes out of his room at night for other than the exceptions, just calmly (and silently) take him back to bed. I had a friend who spent 1 week after the transition peering under the closed door, watching for little feet getting out of bed so she could say "stay in bed" (through the door). She would watch until she was sure they were asleep. She swears it only takes one week, and after that they think you have amazing powers to know they are getting out of bed. If that doesn't work, a safety lock on the knob could prevent him from leaving his room (it didn't work for me, my son had already figured them out). What did work for me was sitting in his room (in a rocking chair, on the end of his bed, on the floor) and reading with a small light (or if I was tired just resting my eyes) until he was asleep. Good luck with the transition.