Over the last two decades Juvenile violent crime has grown almost twice as quickly as that of adults. This paper finds that changes in relative punishments can account for 60 percent of that differential. Juvenile offenders are at least as responsive to criminal sanctions as adults. Sharp drops in crime at the age of majority suggest that deferrence (and not merely incapacitation) plays an important role. There does not, however, appear to be a strong relationship between the punitiveness of the juvenile justice system that a cohort faces and the extent of criminal involvement for that cohort later in life.