This paper describes the evolution of the juvenile justice system in Portugal since 1911 and analyzes the underlying logics of the three periods that characterize it. The first period extends from 1911 to the reform of 1962. During this period, approaches to juvenile justice were designed and spread. These were based on a paternalist-repressive logic focused on a degeneration-dangerousness model of explanation. The second stage was characterized by a protection logic that, after the changes introduced in 1978, followed the welfare model. The crisis of this stage culminated in the recent modifications to the system implemented under the two laws of 1999: the protection law for at-risk youth and the educational law for juvenile delinquents. Although it is too early to assess the impact of these recent changes, this paper discusses their meaning, placing them in the wider context of the management of social problems.