My 7 yo had this issue but mostly bedwetting. The pediatrician says boys' urinary systems don't fully mature until about age 7, and true enough the incidents have become less frequent to currently rare. He couldn't help what his body wasn't ready for. We just reminded him to urinate throught the evening and right before bed, limited fluid intake in the evenings. And remained very patient, if it's truly his body not able to "hold it", we weren't going to hurt his feelings by being angry or reprimanding him. Maybe you could speak with your son's teacher and make sure she reminds him to go to the restroom at intervals, with a gentle tone. Embarrassment and shyness may have something to do with the problem. Being shy may make him say he doesn't have to go when he does. And never punish for it, they are developing their self esteem, and it could make the problem worse. I also found that reminding him to go, but not reminding of the bedwetting, kind of making it out as not that big of a deal, seemed to help. Letting him know it wasn't his fault, he's ok, and that I'm not disappointed in him when it happened. That seemed to give him more confidence and encouraged him positively to get over the problem. His dad was a little rougher sometimes and hurt his ego, and he seemed to have more rather than less episodes with that technique. Anyways, good luck!