In this essay (from Crime and Justice: A Review of Research), authors Michael Tonry and Joan Petersilia discuss some of the effects of current sentencing and corrections policies that have led to the dramatic rise in the prison population. Included are a discussion of whether imprisonment can reduce crime; the impact of imprisonment on the lives prisoners (including later involvement in crime), their families, and their communities; the changing nature of the inmate population; new trends in prison management; and the politicization of the prisons issue.