This chapter explores the concept of a Dominant Language Constellation (DLC) in a Canadian context and links it to family language policy (FLP) and language of schooling. The focus is on the province of Ontario where English is the majority language and French a minority language, along with various other minority languages, including heritage/immigrant languages and Indigenous languages, spoken in families and communities. In this rich context, FLP plays an important role in the transmission and maintenance of minority languages. Beyond primary language socialization at the family level, however, an important and powerful factor that also influences a child's linguistic trajectory is the choice of language of schooling (typically English or French) made by parents. I report results from a mixed-methods study involving questionnaire data from the families of 170 school-age children growing up as bilinguals or multilinguals and follow-up interview data from a subset of 20 families. The analysis identifies an interplay of family internal strategies and school language choices that influence children's DLCs in important ways and account for differences in bilingual and multilingual constellations (i.e. number of languages), language dominance, passive versus active bi/multilingualism, and changes in constellation configurations over time. [For the complete volume, "Dominant Language Constellations Approach in Education and Language Acquisition. Educational Linguistics. Volume 51," see ED660754.]