The following quotes are pulled from various articles I found via google.com:
"There are a lot of reasons that children refuse to sleep in their own bed. Comfort, separation anxiety loneliness, nightmares, etc. But if you don't break this habit early, it just gets more difficult to do so."
"Don't give in. When your child gets out of their bed, make sure their alright, reassure them, and place them back in their own bed. This can be very difficult and frustrating but by being assertive and taking control of the situation you will show your child that they need to sleep in their own bed. Don't get upset with them because they resist, instead be calm and assuring."
"In general, both sleep consultants and parents who've been there say that once you decide to start this sleep training, bed sharing needs to end entirely. No "Well, just for five minutes" or "Maybe tonight because she had a long day." That means midnight visitors get walked back to their rooms, tucked in, kissed, and left behind. No extra snuggles, no drinks of water, as many times as it takes. There will be screams and sobs, and kids so resistant you'll have to carry them, wriggling and accusing all the way, to their beds. Which they will jump out of in a split second. You will start to wonder if you will ever sleep again. You will; just maybe not tonight. Keep this up until the new rules sink in."
"Giving in to whining, crying, or tantrums will only reinforce that strategy as a way to coerce to into changing your mind any time your kids wish to influence you."
"Just remember that no matter what the reason do not let the child sleep in your bed or else they will keep finding new excuses to do this. If my child has a nightmare, I will go to their room and lay down with them until they fall asleep. When you lay in the child's bed, it is letting them know that they still have to sleep in their own bed but you will be there to comfort them when something bad happens. "
"It does not work well to tell children to sleep in their bed and then relent when they act up. This only teaches them that their persistence will be rewarded with a trip to your bed."
"Don't weaken to crying or whining. If you do, your child wins. Tell your child you are not going to keep coming in for kisses, hugs, discussion, begging, or pleading. Stick to this. If your child leaves the room, simply re-direct the child back without discussion. Show no weakness, or your child will know that this behavior results in a change."
Basically, I was right. I told Danny that she was going to throw tantrums and cry and test him to the limit. I told him that if he gave in she would always know that she can cry until he gives in. And he just gave up and blamed me. Even though less than five minutes after she was screaming and crying, she was sitting in front of the television laughing and playing with her dolls. I didn't expect her to really sleep in her own bed, it was more of an experiment/attempt. I am more disappointed that she disrespected both of us by saying mean things and throwing a violent tantrum with her father. In the end, if she has to sleep in her princess bed beside our bed then so be it. We will work it out eventually.