Policymakers and other stakeholders can use cost-benefit analysis as an informative tool for decisionmaking for substance abuse prevention. This report reveals the importance of supporting effective prevention programs as part of a comprehensive substance abuse prevention strategy. The following patterns of use, their attendant costs, and the potential cost savings are analyzed: - Extent of substance abuse among youth - Costs of substance abuse to the Nation and to States - Cost savings that could be gained if effective prevention policies, programs, and services were implemented nationwide - Programs and policies that are most cost beneficial