Toilet training (also potty training or toilet learning) is the process of training someone, particularly a toddler or infant, to use the toilet for urination and defecation. Attitudes toward training in recent history have fluctuated substantially, and may vary across cultures and according to demographics. Many of the contemporary approaches to toilet training favor a behaviouralism- and cognitive psychology-based approach.

Specific recommendations on techniques vary considerably, although a range of these are generally considered effective, and specific research on their comparative effectiveness is lacking. No single approach may be universally effective, either across learners or for the same learner across time, and trainers may need to adjust their techniques according to what is most effective in their situation. Training may begin shortly after birth in some cultures. However, in much of the developed world this occurs between the age of 18 months and two years, with the majority of children fully trained by age four, although many children may still experience occasional accidents.

Certain behavioral or medical disorders may affect toilet training, and extend the time and effort necessary for successful completion. In certain circumstances, these will require professional intervention by a medical professional. However, this is rare and even for those children who face difficulties in training, the vast majority of children can be successfully trained.

Children may face certain risks associated with training, such as slips or falling toilet seats, and toilet training may act in some circumstances as a trigger for abuse. Certain technologies have been developed for use in toilet training, some specialized and others commonly used.