The major objective of the Six-year Follow-up Study on Career Criminals was to provide data describing the effects of sentencing decisions on the behavior of career criminals. A second purpose was to develop programs to target career offenders at the time of sentencing who were likely to commit crimes in the future and incarcerate them accordingly. The data collection includes detailed demographic background and complete prior and follow-up criminal records for each selected offender. There are two types of data sets in the study, the PSI data set based on pre-sentence investigation (PSI) reports, and the Parole data set based on Parole Commission records. The PSI data set describes each offender's demographic background, criminal history, and court entry/exit history. The Parole data set contains information about the offender's background characteristics, prior records of arrests, convictions, dispositions and sentences, and follow-up records for a period of six years. Arrests are described in terms of arrest date, offense charge, disposition, result of sentence, and months incarcerated.