This article examines the language practices of teachers and students in a Ukrainian complementary school, and the language ideologies influencing teachers’ responses to students’ language practices in a Ukrainian complementary school. The data presented in this analysis comprise a collection of fieldnotes collected over the course of one academic year in a Ukrainian complementary school located in the Midlands, England. The analysis of these data identifies the presence of two seemingly contradictory language ideologies—separate bilingualism and flexible bilingualism—seemingly coexist in the complementary school, implied through teachers’ and students’ language practices and teachers’ responses to students’ language choice. The analysis also considers the use of Russian in the Ukrainian complementary school, thus exploring the use of a language other than the heritage language (Ukrainian) and the societal majority language (English) in this setting, highlighting the linguistic diversity within this context.