The development and clinical course of night terrors and the personality patterns of patients with this disorder were evaluated in 40 adults who had a current complaint of night terrors. Compared with a group of adult sleepwalkers, the patients with night terrors had a later age of onset for their disorder, a higher frequency of events, and an earlier time of night for the occurrence of episodes. Both groups had high levels of psychopathology, with higher values for the night terror group. This sleepwalkers showed active, outwardly directed behavioral patterns, whereas the night terror patients showed an inhibition of outward expressions of aggression and a predominance of anxiety, depression, tendencies obsessive-compulsive/, and phobicness. Although night terrors and sleepwalking in childhood seem to be related primarily to genetic and developmental factors, their persistence and especially their onset in adulthood are found to be related more to psychological factors.