A central tension which overwhelms extant systems of youth justice is the requirement to meet the needs of the troubled and vulnerable young offender at the same time as meeting the needs of society. It is imperative that these tensions be reconciled. To address this challenge, this chapter is divided into three parts. Part 1 explores the evolving theoretical/philosophical frameworks around which debates on youth justice have been conducted; examines the range of outcomes which extant youth justice systems seek to achieve; and briefly overviews the key components of international norms and conventions. Part 2 explores in more detail variant models of youth justice (in terms of institutional infrastructure), in the course of which some of the key differences between systems internationally are highlighted. Part 3 explores the links between system and context and the problems that this may pose for policy reform. The chapter concludes with a review of the policy implications. Tables, notes, and references