In Germany, kindergarten and primary school belong to different systems, and each follow their own traditional logic, mandates, and organisational structures. Due to this, children experience transition to school as one of the major changes in their young lives. Up to now, empirical data show a great social injustice in education in Germany. Pupils’ success in school still heavily depends on their family’s socio-economic and ethnic background. In the last 25 years, efforts were undertaken to improve connectivity between kindergarten and primary school. This chapter gives an overview of significant developments and main research findings on optimising transition to school on the basis of three key events that are analysed as social and educational ‘game changers’: PISA 2000; the ratification of the UN convention on the rights of persons with disabilities in 2009; and recent findings of competence studies among primary schoolers since 2022. All have had a significant impact on research, policy, and practice in the organisation of transition and have provided impulses for new developments. Along the chronology of these ‘game changers’, the chapter analyses key lines of discourse and presents established knowledge, consensus, and ongoing controversies in the German educational debate about transition to school in the last 25 years.