The study investigates violent offenders in a true birth cohort consisting of all male children (n=31,436) born to mothers in Copenhagen, Denmark, between January 1, 1944, and December 31, 1947. Offenses categorized as violent were murder, rape, violence against authority, bodily injury, and robbery with violence or the threat of violence. Criminal records on each of the subjects were obtained from police files. Arrests for 10,918 of the 28,879 men still living in Denmark in 1974 showed that 6.7 percent of the arrestees (2.5 percent of the cohort) were charged with violent crimes. Of the violent offenders, 76.5 percent did not commit a second violent offense. The bulk of the violent offenses were assault and robbery, and the violent offenders tended to commit more crimes than other offenders in the cohort, while the offenses of the violent offender tended to be more serious. Violent offenses among the cohort rose sharply from age 16 to age 18, where violent offenses remained fairly stable until they increased slightly and peaked at age 25, followed by a sharp decline. Repeat violent offenders tended to specialize in offenses of violence. Tabular data and 13 references are provided.