For agencies seeking to assess and document diversion program efficacy, this guide provides an overview of the key data elements, types of study designs, and the questions to consider. Agencies can use the findings from well-designed, rigorous evaluation endeavors to inform major decisions like program operations and how to improve services. For example, a well-designed study can inform programmatic details like changing diversion conditions, reconfiguring eligibility criteria, or even shifting resources to another more promising program.