needed to offset excessive growth in prison populations in that state arising from continuing increases in Q_i.

Whether measured by raw counts of inmates, by population rates, or in relation to crimes committed, the use of incarceration has increased substantially in the United States since the mid-1970s. In this section, we explore the likely impact of these changes in sanction policies on levels of violent crime. Aside from retribution (or punishment), incarceration also serves crime control purposes, operating directly through incapacitation to prevent crimes by those incarcerated offenders who are physically removed from the community, or indirectly through the deterrence (i.e., inhibiting) effects of threatened incarceration on offenders who are not now in prison.

Incapacitation and deterrence interact in important ways to reduce the overall level of crime. Despite an extensive body of empirical research, no prior studies satisfactorily estimate these two effects.²⁵ Numerous studies provide estimates of the elasticity of crime to changes in sanction levels. To the extent that estimates of the ''deterrence" elasticity refer to imprisonment sanctions, however, they really reflect the combined effects of deterrence and incapacitation. Incapacitation estimates, by contrast, fail to incorporate deterrence effects that may substantially reduce the individual offending levels from which incapacitation is measured.

The discussion below focuses mainly on the incapacitation effects of incarceration and offers important new advances over previous estimates. We also consider, in an exploratory way, recalibrating these incapacitation estimates to accommodate the impact of deterrence on base offending levels.

As with other forms of crime, any single violent offense rarely leads to incarceration of its perpetrator. Thus, at any point in time, only a small fraction of offenders who engage in violent crimes are imprisoned and incapacitated from further victimizing individuals in the community. Yet, the reduction in violent crimes attributable to incapacitation need not be negligible, since a relatively

Front Matter (R1-R8)

Public Perceptions and Reactions to Violent Offending and Victimization (1-66)

The Costs and Consequences of Violent Behavior in the United States (67-166)

Violence and Intentional Injuries: Criminal Justice and Public Health Perspectives on an Urgent National Problem (167-216)

Predicting Violent Behavior and Classifying Violent Offenders (217-295)

Incarceration and Violent Crime: 1965-1988 (296-388)

Index (389-397)