Don't blow up when you see a telltale puddle under or near your "toilet trained" toddler. Instead, point it out, express your regret, quickly change his clothes, help him wipe up the puddle, and put the wet things in the laundry. Your child can and should help clean up, but don't turn the experience into a guilt trip. Yelling and long discussions won't help, either.
Children really can't say why accidents happen, so don't press your child for explanations. One common cause of accidents is sheer forgetfulness: Children this age can get so caught up in an activity that they forget to pay attention to the signals their bladder is sending them. Or they might be under stress from a big change a new day care setting, for example, or a baby in the house. Young children lack insight into their own behavior, but they do need to know how to handle the problem when it occurs. That's why enlisting your toddler's help in accident cleanup is so important.
Learn more about accidents and other toilet training challenges.