Potty training varies by culture. Some cultures will have their children potty trained by 1-2 years but it takes a lot of work and continuous effort. Americans traditionally allow their children to potty train at their own pace and some boys are especially difficult. Most boys and girls will train on their own with parental encouragement by age 3 yrs. However, some boys in particular can be very resistant to training and that is not uncommon. Some don't train until 3 1/2 years and a few not until 4 yrs. So, yes, it is not uncommon for boys to still wear diapers at 3 yrs of age. When it gets to the point of confrontation with your son over this issue, you're probably not going to get far. It's a game of wills...yours vs. his. He CAN train, but he doesn't want to, so you have to give him an incentive. I tell my patients to tell a child like yours to express your deep sadness (not anger) and say, "Oh...I am SO disappointed you are still acting like a baby. You can feign crying even. If he EVER does it right, then act EXTREMELY EXCITED and praise him to high heavens. Also, this may be one time you can bribe your son by going to any superstore and buying a bag of toy cars or something he really likes, even candy and then putting the prize items high up on a shelf where he can see them, but not get them. Continually tell him that when he poops in the potty, he will get a treat! And continuously tell him how happy and proud you will be when he acts like a BIG BOY and not a little baby because BIG BOYS get to do special things like go for ice cream or to pick out a toy at a store, but BABIES can't do things like that.