This introduction provides the framework for the special issue by describing the social inclusion agenda of neoliberal market democracies. While the social inclusion agenda has been widely adopted, social inclusion policies are often blind to the ways in which language proficiency and language ideologies mediate social inclusion in linguistically diverse societies. If language is written into social inclusion policies, it is often done in a top-down manner informed by linguistic ideologies of monolingualism and linguistic discreteness rather than an informed understanding of the realities of communication in linguistically diverse societies. By contrast, the contributors to this special issue draw on ethnographic case studies to show that the key linguistic challenge of the social inclusion agenda is the promotion of inclusive language ideologies and language practices that value diversity. We end the introduction by elucidating implications for policy and research.