This study examines transitions to school from the standpoint of the work of families. We identify systemic differences constructed through state responses to childhood disability. Based on data from a longitudinal institutional ethnography conducted in Ontario, Canada, these differences illuminate the ways in which ability and disability are constructed in early childhood, and how these constructs are reinforced through procedures, policies, and documentation. Ultimately, we identify five key phenomena in the study: implicit messages of exclusion, the work of families, the supremacy of labels, a fallacy of choice, and the flexibility of institutions to adapt for children. These findings are taken up in the context of broader discourses of school readiness and transition to school with the intention of expanding our conversation about transitions.