In this prospective study, the authors predicted violence and homicide in 3 representative school samples (N = 1,517). Participants were part of a longitudinal, multiple cohort study on the development of delinquency in boys from late childhood to early adulthood in Pittsburgh, Pennsylvania. Thirty-three participants were convicted of homicide, 193 participants were convicted of serious violence, whereas another 498 participants self-reported serious violence. Predictors of violence included risk factors in the domains of child, family, school, and demographic characteristics. Boys with 4 or more violence risk factors were 6 times more likely to later commit violence in comparison with boys with fewer than 4 risk factors (odds ratio [OR] = 6.05). A subset of risk factors related to violence also predicted homicide among violent offenders. Boys with 4 or more risk factors for homicide were 14 times more likely to later commit homicide than violent individuals with fewer than 4 risk factors (OR = 14.48). Implications for the prevention of violence and homicide are discussed.