Evaluation findings were developed in association with the following assumptions underlying the program: (1) the existence, the identifiability, and the criminal justice contact with a subpopulation of serious repeat offenders who commit a disproportionate amount of crime; (2) the ability of the prosecutor to provide specialized, intensified attention to a select subgroup of criminal defendants; (3) the impact that specialized prosecutorial attention might have on the performance of the criminal justice system; (4) the impact on crime of the incapacitation effect achieved through increasing the conviction and the incarceration of this active subpopulation of criminal defendants. Beyond general support for targeting career criminals, considerable diversity was found among the four offices in how they defined their career criminal population. None of the offices used information derived from research in other jurisdictions. While local autonomy in defining the target population appears to have aided in program acceptance, implementation, diffusion, and institutionalization, it fostered diversity among the career criminal populations selected for special handling, none of which were defined based upon predictions of recidivism. Findings showed that few changes in disposition mode and type of career criminal defendants were associated with the programs analyzed. Improvement in the strength of career criminal convictions was observed in two jurisdictions, an improvement that was accompanied by the imposition of longer sentences for career criminals in one site. Changes in crime level effects due to increased incapacitation could not be demonstrated in the four jurisdictions. This may be due to the fact that the programs generally involved an intensification of effort or organization rather than any radical departure from the kinds of activities normally undertaken for routine prosecutions. Footnotes are provided.