In the ERC-CoG INTRANSITION project, I examine how interactions with parents and friends affect adolescents’ identity, autonomy and psychosocial adjustment during school transitions from elementary to secondary education and from secondary to tertiary education. The project will examine intra-individual (or within-person, as opposed to inter-individual or between-person) processes of change in identity and autonomy at different time scales: moment-to-moment behaviour during interactions with parents and friends, relational experiences across hours and days, and long-term development. This project particularly increases our understanding of developmental processes of identity and autonomy at individual level that drive developmental changes during transitional periods.