This introduction outlines the analytical approach informing the articles presented in this special issue. The project of 'generationing' development involves re-thinking development as distinctly generational in its dynamics. For this, we adopt a relational approach to the study of young people in development, which overcomes the limitations inherent to common categorising approaches. Concepts of age and generation are employed to conceptualise young people as social actors and life phases such as childhood and youth in relational terms. Acknowledging the centrality of young people in social reproduction puts them at the heart of development studies and leads the articles comprising this special issue to explore how young people's agency shapes and is shaped by the changing terms of social reproduction brought about by development. © 2014 European Association of Development Research and Training Institutes 0957-8811.