Using an information theoretic approach, the data reveal a fair amount of variation among individuals both in terms of the number of crimes averted by their incarceration and the responsiveness of these estimates to longer incarceration terms. Estimates were found not to vary substantially across demographic groups defined by offender race, gender, or ethnicity; variations across States and offense types were more pronounced. Implications of the findings are discussed. Although incarceration can, and presumably does, have other effects on crime, this paper addresses only the incapacitation effect. The paper begins with a brief review of the literature. This is followed by a nontechnical overview of the analytical framework. After describing the data used in this study, the paper than presents the main findings with a discussion of their implications. The paper concludes with a discussion relating findings reported in this paper with those reported elsewhere in the literature, and enumerates some promising directions for future research. The paper developed an information theoretic approach for modeling the criminal history accumulation process of a sample of prison releasees. Separate models were estimated for two crime categories, crimes against persons and property related crimes. The models were used to simulate the anticipated effects of increasing prison terms for all individuals. Figures, tables, and references