A review of the factors that have influenced the decline in homicides, particularly by juveniles, focuses on the role of weapons, the impact of drug-market activity and intensity, the incapacitative and deterrent effects of incarceration on adult homicides, and changing demographic composition. The paper suggests that factors identified in the current decrease in violent crime should be taken into account in crime-control priorities designed to forestall another crime increase. In discussing issues in the diagnosis of juvenile psychopathy for the purpose of determining the nature and severity of juvenile dispositions, a second paper argues that the validity, stability, and predictive utility of the primary testing instrument (the Psychopathy Checklist Youth Version) for juvenile psychopathy have not been adequately determined through longitudinal research. The paper on the development of violence prevention programs notes the importance of tailoring programs to various types of violence and targeting programs to the context of ethnic groups where various types of violence are prevalent. Basic principles for violence-prevention strategies are also identified and discussed. The concluding paper reviews the history of the impact of DNA profiling on standards for the admission of scientific products as evidence. The paper argues that the emergence of DNA science in the crucial role of placing or excluding a suspect or defendant at a crime scene has resulted in more stringent quality assurance and performance measures not only for DNA laboratories but also for crime laboratories in general. Question-and-answer sessions and notes accompany the papers.