THE CONSTRUCTS OF ‘THREE WORLDS’ and culture-switching were developed during a longitudinal study of the literacy experiences of a small group of culturally diverse children in Australia who encountered differing social and cultural contexts as they were transitioning from preschool to Year 1. Drawing on sociocultural perspectives and using a case study design, the report examines the ways in which five children negotiated culture, literacy, and schooling at home and in the classroom. The study establishes sufficient evidential warrant for further investigation into the nature and dimensions of world-building and culture-switching that seemingly characterise such literacy experiences. It may also provide insights for teachers of young, culturally diverse children starting school.