This report, prepared through research conducted by ICF International, presents the results of National Cooperative Highway Research Program (NCHRP) Project 20-65 Task 24, “State Department of Transportation Role in the Implementation of Transportation Demand Management Programs.” It explores examples of successful implementation and support of transportation demand management (TDM) programs by state departments of transportation (DOTs). It is designed to be used as a primer for states to use in implementing TDM programs and includes a set of case studies, examining the range of ways that state DOTs encourage TDM services.