According to the Uniform Crime Reports, violent crime rates increased significantly over the last two decades. In contrast, National Crime Victimization Survey data indicate that the rates of violent crime remained relatively stable or declined during this period. Which series provides a correct estimate of trends in crime rates is of more than academic interest, because highly publicized statistics influence both public attitudes toward crime and policy decisions. The research focused on rapes of females, robberies, and aggravated assaults, as well as Uniform Crime Report homicides and violent crimes. The analysis indicated that changes in police agencies rather than changes in the rates of violent crimes have created the upward trend in Uniform Crime Report violent crime rates during the past two decades. The period studied was one of continually increasing police productivity in terms of the recording of crimes that occurred. Figures, tables, and 37 references (Author abstract modified)