The role of the ego in sleepwalking is discussed and seven illustrative cases are presented. One adult was studied over a period of five years and six children were studied less intensively. The author found that an important aspect of sleepwalking is its service as partial defense against sleep itself. Sleep is frightening because it is associated with loss of control, loss of identity, and death, and the somnambulism serves to decrease these anxieties. Problems in expression of aggression, independence, and differentiation from the parents are found and, while the patients are outwardly compliant in waking life, they express these drives dramatically in sleepwalking.