R..
When my DD was younger I had to transition her back into her crib... I just did it slowly. I would put her in when she was sound asleep. If she woke up, I would get her asleep again and do it over again (repeat repeat repeat. lol) When she got used to that, I would let her get ALMOST asleep (eyes in that 'drifting shut' stage) and do that over and over until she got used to it. I just put her down more and more awake, so now I can put her in when she's just drowsy and she will fall asleep on her own. (except lately... She has learned to cruise the crib, so now it's a little bit of a battle. It's more fun to play than to sleep apparently!) I tried CIO too... but only lasted 2 days. lol.