Contemporary concerns in mathematics education recognize that in the increasingly technological and globalized world, with concomitant change in population demographics (e. g. immigration, urbanization) and a change in the status of languages (e. g. English as a dominant language of science and technology) multilingualism in classrooms is a norm rather than an exception. Shifts in perspective also view language not simply as an instrument for cognition with all learners equipped with this instrument in service of learning, although clearly in the classroom that remains of importance. Rather, it is now also being acknowledged that language use is inherently political, so that the language that gets official recognition in the classroom is invariably the language of the powerful elite, or the dominant societal language, or in the case of post colonial contexts the language of the colonisers. From this socio-political role of language in learning quite different issues arise for teaching, learning and curriculum for linguistically marginalized learners than that of cognition (e. g. immigrants, second language learners, other). Policies on language in education are being considered and re-considered with specific reference to mathematics teaching and learning. Given the policy environment, globally the proposed publication is timely. This edited collection draws on recent, emerging insights and understandings about the approaches to improving policy and practice in mathematics education and mathematics teacher education in multilingual settings. It presents, and discusses critically, examples of work from a range of contexts and uses these examples to draw out key issues for research in education in language diverse settings including teaching, learning, curriculum and fit these with appropriate policy and equity approaches.