Five important changes can be detected in the homicidal crime of Finland and Sweden. From the mid-17th century to the mid-18th century, concurring with the establishing of the modern centralized state, homicide rates dropped significantly. In the long term, the local variation in Swedish homicide rates decreased, probably because of the rise of the centralized state; however, the case was different in Finland, partly because of a less efficient central administration before the 20th century. During the period 1700-2000, there was a clear social marginalization of lethal violence; this change took place earlier in Sweden than in Finland. There was a relative shift from instrumental (economy-related) to expressive violence. In the 20th century, concurring with general urbanization, there was a considerable privatization of lethal violence in both countries as homicides moved from public places to private. The social and historical data suggest that homicide participants may have become more deviant from the mainstream society than they used to be. Overall, Nordic homicidal crime has had two major components since the early modern period. The high offending rates of the marginal lowest-stratum male population have been a stable phenomenon for five centuries. Sudden changes in homicide rates have typically been caused by young males with more heterogeneous social backgrounds. (Published Abstract)