This dissertation analyses the regulation of youth employment in and by the EU. By youth employment regulation, I refer to the legal, policy and other instruments establishing a regulatory framework for young people’s transitions to work. I find that, since 1957, the EU attempts to regulate youth employment through three policy locations, put differently, threads: young people’s geographical mobility; their working conditions and work relations - youth employment law; and instruments aimed at young people’s integration into the labour market - youth employment policy. The dissertation evaluates EU youth employment regulation and its over time varying contours through three frames. First, I trace the threads’ interactions which show how social Europe’s policy locations have been mobilised in broader governance arrangements for youth employment regulation. Second, I examine the area’s Europeanisation, i.e., the capacity of EU governance arrangements to orient and de facto change domestic youth employment regulation. Third, I assess the normative ambitions of EU youth employment regulation. The thesis argues for youth employment regulation that empowers personal development, but also realises public institutions and private actors’ responsibilities to regulate the structural pressures that determine the outcomes of work transitions. Thereby, my focus on young people’s work transitions adjusts existing macro-level characterisations of social Europe, its timeline, governance arrangements and normative ambitions. It also contributes to foundational debates on labour regulation, such as the classification of work and the access to labour and social rights, the flexibilisation of labour markets and the rise of precarious work, the individualisation of labour regulation, and the role of employment policy and other policy locations outside labour law narrowly understood for this regulatory field. This analysis helps in understanding how EU regulation constitutes young people’s work transitions.