The Standardized Program Evaluation Protocol (SPEP) is a rating instrument for assessing programs for juvenile offenders with regard to their expected effectiveness for reducing recidivism. In the fall of 2006, a version of the SPEP was adapted for Arizona programs serving probationers under a contract between the Administrative Office of the Courts (AOC), Juvenile Justice Services Division (JJSD), and the Center for Evaluation Research and Methodology at Vanderbilt University.

The SPEP is based on research studies of programs for juvenile offenders drawn from an archive of nearly 600 controlled studies of effects on recidivism assembled by Dr. Mark Lipsey, Director of the Vanderbilt Center for Evaluation Research and Methodology. Using a technique known as meta-analysis, the characteristics of the programs with the largest effects on recidivism have been identified from that research and translated into guidelines for effective interventions. Based on those guidelines, the SPEP is designed to rate programs according to how closely their characteristics resemble the characteristics shown by research to be most strongly associated with recidivism reductions.