The first source documented offenders sentenced in 1976-77; the second provided followup information from ongoing records of arrests since 1972 and their subsequent outcomes through the various stages of criminal processing. Data were unequivocally matched from the two data sources on 257 assault and 307 burglary cases. The results suggest that the sentences which were given do not appear to have exerted much influence on later offender behavior, i.e., there was no evidence of any rehabilitative and/or special deterrent effects of sentencing. Moreover, there was no firm sign of any incapacitative effects of typical prison and jail sentences. That is, groups of persons who were comparable (with respect to their offense or conviction and their likelihood of engaging in future criminal behavior) to the incarcerated group, but who were not incarcerated, committed new offenses at about the same rate, and over the same periods, as the incarcerated ones. This demonstration study has shown that this kind of investigation (combining and analyzing data from two different sources to ascertain effects over time) is feasible. It is recommended that similar research be done on a larger scale. Tabular data and charts are given. A technical report on the categorization of offenses is appended.