The good news is that your son HAS used the toilet before. I've had a similar issue with my 4yr old. Totally potty trained during the day, but recently started peeing in his pants again. Usually it was because he was so focused on his electronic toys or tv to stop and miss out on the fun to use the toilet. He only did this at home...never at school, therapy, or outings. He doesn't like to use the toilet in other places to poop and usually holds it till we get home. A couple of times he almost pooped in his pants at home, but we were able to see visual cues and rush him to the toilet. Anytime he is playing with something and he forgets to use the toilet, he looses that item and earns it back only when he successfully uses the toilet with clean pants. He is highly praised when he pees in the toilet and we are still using a reward chart for when he poops in the toilet.

He is not constipated. He doesn't do it at school. I should probably just watch him more closely. He just seems to not want to use the toilet. I'm alittle leary of having him clean up the mess. But if it'll make him go on the toilet.I'll give it a try.

...one more thing. When my son would poop in his pants, he had to clean up his mess. He has tactile issues, so he REALLY didn't like getting his hands dirty. I was assured by an expert in the field that this is a technique used and is appropriate. Good luck :)

Is he constipated?? I had this issue with my daughter and found out that she was constipated and didn't want to take the time to sit on the toilet. Instead she would start where ever and then go the bathroom. We put her on sustanex to make sure she stays regular and we have not had the issue since.