Longitudinal studies that follow children into adult life have had two major thrusts: (1) to learn whether personality traits have long-term stability; and (2) to identify early predictors of adverse outcomes. Deciding whether personality traits are stable has been problematic because the same trait may be expressed differently at various ages. On the other hand, the goal of finding childhood predictors of adult outcomes has been met. A syndrome of adverse outcomes, including crime, low occupational achievement, substance abuse, and marital instability, is clearly predicted by a child's antisocial, noncooperative, or confrontive behavior. Childhood behavior problems are linked to the display in adulthood of a general failure to conform to adult norms, and the role of family pathology in adult nonconformity is almost as clear. The predictive power of childhood problems other than antisocial and confrontive behavior for adult life has not been as well substantiated. The longitudinal studies specifically look at childhood personality and the prediction of life course patterns, adopted and illegitimate children growing up, long-term criminal outcomes of hyperactivity and other conduct difficulties in childhood, processes in the development of persistent offending, and parental absence. The studies also examine adult outcomes of institution-reared children, antecedents and consequences of cocaine use, conduct problems as predictors of substance abuse, adolescent psychopathology and problem behavior, continuities in psychiatric disorders from childhood to adulthood, early life psychosocial events and adult affective symptoms, schizophrenia in children at risk, and high-risk children in adolescence and young adulthood. References, tables, and figures.