This project extends an ongoing study of homicides in New York City across 200 years. An unexpected finding from that research was that nineteenth century age rates of homicide victims and perpetrators were flat across the age range 17-55. This difference may have obtained during the mid twentieth century. Current data indicate that the rate peaks during this age period. Of verify and replicate this result, the current research will collect data at additional sites across the united states. The purpose of the project, therefore, is to determine if it is a general phenomenon or unique to a few locations and eras. In addition, the results will assist in differentiating how much of the changes in homicide are due to changes in demographic composition of the City and how much is due to changes in behavior. Qualitative and regression analyses are being used. If changes in over all homicide rates are driven by age rate offending as well as basic demographic composition of the population, violence researchers will need an more complex analysis than previously presumed. Results of this work have already had and are expected to continue to have a major impact on sociolegal theorizing about the factors that contribute to violence and to policy makers who hope to intervene to reduce violence. %%% This project extends an ongoing study of homicides in New York City across 200 years. An unexpected finding from that research was that nineteenth century age rates of homicide victims and perpetrators were flat across the age range 17-55. This difference may have obtained during the mid twentieth century. Current data indicate that the rate peaks during this age period. Of verify and replicate this result, the current research will collect data at additional sites across the united states. The purpose of the project, therefore, is to determine if it is a general phenomenon or unique to a few locations and eras. In addition, the results will assist in differentiating how much of the changes in homicide are due to changes in demographic composition of the City and how much is due to changes in behavior. Qualitative and regression analyses are being used. If changes in over all homicide rates are driven by age rate offending as well as basic demographic composition of the population, violence researchers will need an more complex analysis than previously presumed. Results of this work have already had and are expected to continue to have a major impact on sociolegal theorizing about the factors that contribute to violence and to policy makers who hope to intervene to reduce violence.