Among 170 preadolescent children (138 males, 32 females) admitted to the University of Iowa Psychiatric Hospital between 1970 and 1983, 23 males (17%), had adult prison records at follow-up in 1990. Assaultive behavior in childhood predicted adult imprisonment (odds ratio = 4.96, 95% confidence interval 1.8-13.8, p = 0.002), as did criminality in a biological parent (odds ratio = 4.0, 95% confidence interval 1.3-12.4, p = 0.015). Diagnosis, including conduct disorder, was not correlated with outcome. Among these young children, male gender, violence, and parental criminality identified persons at high risk for adult imprisonment. Psychiatric hospitalization in childhood is a risk factor for adult disturbance, including sociopathy.