The education system is a key site for the organization and legitimization of linguistic resources and for socializing children according to existing norms and understandings of language and diversity. In Galicia, an autonomous community of Spain, language policies designed to address linguistic diversity have emerged separately, through different historical processes. Spanish (as the national, majority language); Galician (as the local minority language); languages spoken by migrant families; and the more globally powerful English are assigned distinct and hierarchical roles in the Galician educational system. Based on a systematic discourse analysis of four key educational policies enacted at the national of autonomic level, our analysis explores how concepts of linguistic and cultural diversity are represented within policy and how languages and language learning are understood. Our results indicate that while these policies employ some explicit discourses that acknowledge and celebrate multilingualism, a careful reading of the ideologies that underpin them are monolingual. Deficit discourses are embedded throughout the policies in so far as linguistic and cultural diversity are frequently associated with special needs and language is positioned as a factor that might contribute to educational deficits. Migrant languages are never framed as assets that could contribute in a positive way to the learning environment. We argue that educational policy—as a social practice of power—must acknowledge and incorporate students full cultural and linguistic repertoires in order to provide the most effective learning. By critically analysing the status quo, we seek inspiration for designing policy from asset rather than deficit perspectives.