This study represents the first systematic research on felony probationers. It is based on data on individuals convicted of selected serious felonies in Superior Court in California, who would have been likely candidates for prison. It defines probation and reviews its history to the present; documents the recidivism behavior of a selected sample of probationers and the implications for public safety; analyzes the factors that influence the prison/probation decision, the consistency of their application, and the recidivism of offenders with low, moderate, and high probabilities of imprisonment; identifies the factors associated with recidivism; discusses intermediate punishment--intensive community-based surveillance--as a sentencing alternative; describes operational programs; and develops a sentencing process to establish which alternative is appropriate for a given offender. Some of the conclusions suggested by the research are (1) felons granted probation present a serious threat to public safety; (2) the factors specified by law as appropriate considerations in the prison/probation decision strongly influence that decision in practice and should be used more consistently; (3) given the information now routinely provided to the court, the ability to predict which felons will succeed on probation cannot be vastly improved; and (4) state criminal justice systems should develop punitive community-based alternatives to prison for convicted felons.