The recidivism of 136 extrafamilial child molesters who had received phallometric assessment in a maximum security psychiatric institution from 1972 to 1983 was determined over an average 6.3-year follow-up. Fifty had participated in behavioral treatment to alter inappropriate sexual age preferences. Thirty-one percent of the subjects were convicted of a new sex offense, 43% committed a violent or sexual offense, and 58% were arrested for some offense or returned to the institution. Subjects convicted of a new sex offense had previously committed more sex offenses, had been admitted to correctional institutions more frequently, were more likely to have been diagnosed as personality disordered, were more likely to have never married, and had shown more inappropriate sexual preferences in initial phallometric assessment than those who had not. Behavioral treatment did not affect recidivism.