This thesis explores young people's experiences of and orientations towards being and becoming. Using focus groups and interviews with participants aged between 11 and 15, the research investigates how young people form a sense of who they are and who they can become in terms of character, temperament, talents, intelligence, humour, appearance and so on. Particular attention is paid to the role of relationality, and especially siblingship, in these processes as well as to how young people themselves make sense of and theorise being and becoming. The research shines analytical and methodological 'spotlights' on key contexts, relationships and modes of thinking which highlight processes of being and becoming in new and interesting ways.A spotlight on the context of secondary school indicates how ways of being and becoming can be created and constrained by the particularities of the environment of school. A spotlight on being and becoming in a group of friends indicates young people's reflexivity about the moralities of being different to friends, despite the largely homophilous nature of these relationships, and reveals some of the ways in which young people's friendships can affect who they are and who they see themselves as becoming in the future. A spotlight on young people's sibling relationships fills a gap in existing knowledge about the role of lateral kin in shaping young people's lives and indicates how siblings can be a source of social capital (for good or ill) in school. It is also argued that being one in a series of siblings can 'fix' aspects of being and becoming in several ways, including through the construction of relational identities in families and through normative ideas about how siblings ought to behave. Finally, the thesis shines a spotlight on young people's understandings of modes of transmission and the nature of personhood, indicating how young people can think in nuanced and complex ways about how being and becoming works.Taken together the spotlights of this thesis indicate how young people form a sense of who they are and who they can become whilst embedded in webs of relationships through time. The thesis demonstrates that, despite being relational and contextual, processes of being and becoming can feel as though they become 'fixed' as the potential for how one can 'turn out' is limited. It is argued that the lay concept of 'turning out' evokes the idea that, although always continuing through time, we will one day 'turn out' and be 'finished'. As such, this thesis suggests that the concept of 'turning out' allows sociologists to think about being and becoming simultaneously. 'Turning out' also encourages an understanding of the social world that embraces ideas which can seem 'contradictory' in sociological terms - such as fixity and malleability, individuality and relationality or genetic and social inheritance. Finally, it is argued that 'turning out' denotes a broader understanding of personhood than those evoked in familiar sociological terms - such as the self, identity and habitus - and incorporates aspects of being and becoming that might otherwise appear somewhat beyond the social.