This inquiry explores how the twofold language policy of a Swedish English-medium preschool is practised in daily interaction. Children (aged 3–4) develop a wider set of code-switching practices than the staff employs in their interaction with the children. The inquiry examines various examples of spontaneous interaction either between staff and children, or amid children playing with each other in the preschool. It is demonstrated how the preschool’s English language profile in practice becomes a bilingual policy, which incites children to learn English and Swedish in the preschool, and diverse ways to handle their bilingualism in the school context. KEYWORDS: Bilingualism, code alternation, monolingual policy, bilingual interaction, child bilingualism