Commissioned by the John D. and Catherine T. MacArthur Foundation Research Network on Adolescent Development and Juvenile Justice, this paper proposes methods for an economic analysis of the nation's separate system of juvenile laws and juvenile courts. Arguments about the value of juvenile justice versus criminal justice traditionally focus on legal principles, adolescent development, and the relative effects of prevention and punishment. This paper suggests adding a cost-benefit approach to the debate. Do the benefits of maintaining a separate legal system for young offenders outweigh the costs? What are those costs and benefits, and can they be measured?