Children's transition to school has been widely investigated, but most studies do not clearly define its starting point. By drawing on the cultural-historical concept of the social situation of development, and selecting 'role adjustment' as the unit of analysis, this paper seeks to clearly define the starting point of children's transition to school. Through a case study of two second-generation Chinese Australian children's role adjustment, this paper finds that it is the qualitative change in children's social situation of development that signifies the starting point of the dramatic adjustment of their role(s). In particular, the starting point of children's first dramatic role adjustment marks the starting point of their transition to school, and the starting points of children's following dramatic role adjustments mark the turning points of their transition to school.