Research on the use of incapacitation strategies to reduce crime has increased rapidly in the last decade. Estimates of the crime reduction potential are numerous and variable, reflecting different assumptions by researchers. This paper reviews and synthesizes studies of collective and selective incapacitation. Sentencing practices in the 1970s and early 1980s prevented an estimated 10 to 30 percent of potential crimes through collective incapacitation strategies. Greater use of incarceration, such as through mandatory minimum sentences, would prevent additional crimes, but prison populations would increase substantially. Selective incapacitation strategies target a small group of convicted offenders, those who are predicted to commit serious crimes at high rates, for incarceration. These high-rate serious offenders, however, are difficult to identify accurately with information currently available in official criminal history records. Preliminary research, assuming moderate accuracy, suggests that select...