This paper argues for a renewed research agenda on the transnational mobility of young people across both youth studies and migration studies. We review key literature across these fields, before arguing for a new conceptual framework that helps to further extend the emerging interdisciplinary space of ‘youth mobility studies’ (Raffaetà, Baldassar and Harris 2016). Our central proposition is that mobility has become an important marker and maker of transitions for youth in many contexts globally. We argue that a conceptual advance is required to understand the unique circumstances of a generation ‘on the move’ as they navigate diverse and non-sequential social, civic and economic practices of ‘adulthood’, and propose the conceptual framework of mobile transitions as a timely new agenda. ‘Mobile transitions’ describes transition pathways under conditions of mobility but also emphasises two key claims around the further development of transnational youth mobility research. The first is the importance of an orientation towards spatio-temporal complexity, multiplicity and fragmentation of both ‘youth transition’ and ‘migrancy’ as scholarly concepts and lived experiences. The second is an argument for understanding ‘mobile transitions’ in relation to three intersecting domains – economic opportunities, social relations and civic practices – rather than through linear notions of the achievement of economic and social autonomy.