Toilet training is a process in which children learn to urinate and have bowel movements in the toilet. Using the toilet is a developmental milestone. This means that it is one of the events that a doctor uses to tell whether a child is developing at a normal pace.

A child must be both physically and emotionally ready before toilet training can succeed. Most children are ready to start when they are about 30 months of age, but some will be ready earlier and others later.

Stress in the home can delay a child's readiness to become toilet-trained. Attempting toilet training if the child is not physically and emotionally ready leads to frustration for both the parents and the child.