Over 90% of parents of toddlers spank or use other forms of corporal punishment. Although the rate declines each year from about age five, this study of a large national sample of U.S. adults found that almost half recalled having been corporally punished during their teen years. This high prevalence indicates a need to investigate the possibility that corporal punishment puts adolescents at increased risk of developing mental health and social relationship problems later in life. The analysis, which controlled for a number of possible confounding risk factors such as low socioeconomic status, found that children who experienced corporal punishment in adolescence had an increased risk later in life of depressive symptoms, suicidal thoughts, alcohol abuse, physical abuse of children, and wife beating. The consistent association of corporal punishment with major adult problem behavior, together with the fact that at least half of all adolescents are victims of corporal punishment by their parents, indicates a need to replicate the study using longitudinal data. If the findings are confirmed, it suggests that a major step in primary prevention of violence and mental health problems can be achieved by a national effort to reduce or eliminate all use of corporal punishment.