I wish I knew...my 2.5 year old daughter is the same! Has no problem peeing on the toilet (although if I don't remind her, she gets lazy and will use her pull-up), but will not poop in the toiler or potty. She poops at unpredictable times, so she has to stay in a pull-up. I have tried going cold turkey and just using underwear, but it didn't help and just resulted in a lot of messy underwear to clean. I even resorted to rewards...which I am basically ethically against for this type of thing...but it didn't work! My two sons potty trained with not much trouble...just did it when they were ready, but this one is a stubborn little thing! I hope some of the other ladies have some advice, I could use it too! I have a feeling it is just a waiting game.