(Revised February 2022)

We examine 70,581 felony court cases filed in Chicago, IL, during the period 1990–2007. We exploit case randomization to assess the impact of judge assignment and sentencing decisions on the arrival of new charges. Our estimates of the impact of incarceration on recidivism show that, in marginal cases, incarceration creates large and lasting reductions in recidivism among first offenders. Yet, among repeat offenders, incarceration sentences for marginal offenders create only modest short-run incapacitation effects and no lasting reductions in the incidence of new felony charges. Our results raise concerns about sentencing reforms, enacted in most states over recent decades, that encourage or mandate incarceration sentences for many offenders with prior criminal records.