Over the recent past there have been several meta-analyses and primary studies that support the importance of the risk principle. Oftentimes these studies, particularly the meta-analyses, are limited in their ability to assess how the actual implementation of the risk principle by correctional agencies affects effectiveness in reducing recidivism. Furthermore, primary studies are typically limited to the assessment of one or two programs, which again limits the types of analyses conducted. This study, using data from two independent studies of 97 correctional programs, investigates how adherence to the risk principle by targeting offenders who are higher risk and varying length of stay and services by level of risk affects program effectiveness in reducing recidivism. Overall, this research indicates that for residential and nonresidential programs, adhering to the risk principle has a strong relationship with a program’s ability to reduce recidivism.