The continua of biliteracy model offers an ecological framework to situate research, teaching, and language policy in multilingual settings. Biliteracy is understood as “any and all instances in which communication occurs in two (or more) languages in or around writing” and the continua as complex, fluid, and interrelated dimensions of communicative repertoires; it is in the dynamic, rapidly changing and sometimes contested spaces along and across the continua that biliteracy use and learning occur. Formulated in the 1980s in the context of a multi-year, comparative ethnography of language policy in two Philadelphia public schools and communities, the model has served in the years since as heuristic in research, teaching, and program development locally, nationally, and internationally in Indigenous, immigrant, diaspora and decolonizing language education contexts. It has evolved and adapted to accommodate both a changing world and a changing scholarly terrain, foregrounding ethnographic monitoring, mapping, ideological and implementational spaces, voice, and translanguaging, antiracist and decolonial pedagogies in multilingual education policy and practice. I trace this trajectory, highlighting experiences in immigrant contexts of Philadelphia and Indigenous contexts of South Africa, Sweden, and Peru where the continua of biliteracy have informed bilingual program development and Indigenous and second language teaching.