Book excerpt: Youths are on trial today in two ways. In the first sense, whereas youths once faced delinquency hearings in juvenile courts, now with increasing frequency they stand trial in criminal courts. In the second sense, recent reforms in juvenile justice have placed the notion of youth itself on trial. Society's trend toward responding to adolescent offenders as adults asks that we set aside traditional presumptions about adolescence as a condition of immaturity that warrants mitigation. The ensuing debate highlights the need for evidence to address whether youths' capacities are sufficiently different from adults to warrant different legal responses to their transgressions.