This chapter focuses on sleepwalking, also known as somnambulism. The symptoms and manifestations that characterize sleepwalking show great variations both within and across predisposed patients. Sleepwalking is more common in childhood than in adulthood, as most children will experience, at least temporarily, one or more of the NREM sleep parasomnias during childhood or early adolescence. Sleep laboratory investigations have yielded considerable information on the polysomnographic characteristics of sleepwalkers. There is a strong genetic component to somnambulism. About 80% of somnambulistic patients have at least one family member affected by this parasomnia, and the prevalence of somnambulism is higher in children of parents with a history of sleepwalking. In addition to the atypical sleep parameters and genetic component reviewed, other factors have been proposed, including psychopathology and deregulation of serotonergic systems. Hypnosis (including self-hypnosis) has been found to be effective in both children and adults presenting with chronic sleepwalking.