In a current world of rapid change and immense global mobility, communities are experiencing unprecedented increases in population diversity that have dramatically heightened the challenge of ensuring social justice for linguistic minorities, including migrants, refugees, and people on the move, with implications for society as a whole. This chapter explores the rhetoric of related policies and practices and the ways in which they respond to the needs of superdiverse communities. The cases of the UK, Europe, and Australia, which all claim their multicultural status and multiculturalism as an important community resource, are discussed. Through an exploration of current research, the effectiveness of languages education policy and planning (LPP) is critiqued to provide a new paradigm that has the capacity to bring attention to and eliminate social injustice in linguistically diverse communities. The chapter argues for the nurturing of new spaces of language use that challenge the monolingual habitus and which can engage the collective autonomy of communities themselves. It conceptualizes how activist languages education can build community capacity and achieve socially just outcomes, thus simultaneously providing a better space for multilingualism and a foundation for peace.