Children's transition to school is a key issue in early years of education. Research in this field points to the counterintuitive possibility that the transition to school may actually lead to a reduction rather than a facilitation of children's agency. The paper presents findings of a longitudinal comparative ethnography on children's transition from fields of early childhood education to primary school in England and Germany. Building on theoretical concepts of the sociology of childhood, the study uses the concept of children's complicity to explore how children's agency is embedded in institutional, interactional orders and how it changes during transition. The findings indicate the importance of the structure of keeping the group of children together during transition. Not only is children's participation in the new social situation in school mediated by peer cultural routines. The paper presents the argument that the complicity children develop with their teachers' expectations takes different forms when they can rely on peer cultural routines. (Contains 4 notes.)