Nocturnal enuresis is a heterogeneous disorder with various underlying pathophysiological mechanisms and causes a mismatch between the nocturnal bladder capacity and the amount of urine produced during sleep at night. It is associated with a simultaneous failure of conscious arousal in response to the sensation of bladder fullness. Generally, a complete history and physical examination, with a specific focus on the genitourinary, gastrointestinal, and neurologic systems, is sufficient to evaluate a patient with enuresis. The therapeutic focus is directed toward a differential approach based on the underlying mechanism and toward combination therapies such as alarm devices and desmopressin as well as anticholinergic agents and desmopressin. Children with increased nocturnal urine production usually have a good response to desmopressin therapy. Patients with a small bladder generally show a poor response to desmopressin treatment, but they would benefit more from combination therapy with enuretic alarm, urotherapy, and antimuscarinic agents in addition to desmopressin. Different types of bladder dysfunction, which result in a small nocturnal bladder capacity, probably contribute significantly to the pathogenesis of nocturnal enuresis, particularly in those with treatment failure and refractory symptoms. Because different clinical subgroups may show different responses to treatment, it is necessary to distinguish these subgroups before a decision on the specific treatment protocol can be made.