Recidivism rates are a growing concern due to the high cost of imprisonment and the high rate of ex-prisoners returning back to prison. The factors leading to recidivism are multifaceted, but one policy-relevant and potentially important contributor is the composition of peer inmates. In this paper, we study the role of peer eﬀects within a correctional facility using data on almost 80,000 individuals serving time in Georgia. We exploit randomness in peer-composition over time within prisons to identify eﬀects of peers on recidivism rates. We ﬁnd no evidence of peer eﬀects for property and drug-related crimes in the general prison population. However, we ﬁnd strong peer eﬀects when we deﬁne peer groups by race and age. Our ﬁndings indicate that homophily plays a large part in determining the strength of peer exposure among prisoners in the same facility. Our ﬁndings suggest that prison assignments can be a way to reduce recidivism for particular groups of prisoners.
First version, October 2, 2019