Findings from this report on the effect of California's "Three Strikes and You're Out" law on the rate of violent crime in the State include the following: analysis of county and statewide data shows that the law has had no demonstrable effect on violent crime rates or trends; that it has had little effect on reducing violent crime rates and trends among targeted populations or jurisdictions; that violent crime rates declined the most among age groups that experienced the least amount of strike sentencing - youths and young adults; and that the counties that used strike sentencing the most did not experience declines in violent crime rates relative to counties that invoked the law the least. The intent of the law was to reduce violent crime by sentencing repeat violent offenders to life in prison. At the time the law was passed, it was thought that counties that used the law the most would see the greatest reductions in rates of violent crimes, especially among targeted populations. To verify the intended effects of the law, the Center on Juvenile and Criminal Justice examined county and statewide data for violent crime, property crime, and all index offenses; arrest statistics for felony and violent offenses; and "Three Strikes" sentencing statistics collected by the California Department of Corrections and Rehabilitation. Analysis of the data found that higher rates of imprisonment for all strikes and third strikes did not lead to significant reductions in all felonies or violent felonies. In addition, the analysis found that many counties used to the law to sentence mainly non-violent offenders, which is counter to the original intent of the law. Recommendations for improving the law are discussed. Tables and references