Introduction Although multilingualism has been the norm throughout human history, we still know very little about the full range of societal multilingualisms. To flesh out the picture, this special issue considers Indigenous contexts where the hierarchical models of multilingualism often naturalised by nation states play a more marginal role (e.g. Fishman 1967; Lüpke 2015, 2016). Current discussions of multilingualism may treat sociolinguistic complexity or 'superdiversity' (e.g. Blommaert 2013; Vertovek 2006) as a relatively new phenomenon; a product of our increasingly mobile and diverse era. Yet these conditions, that have long existed in more 'peripheral' local language communities, seem to be simply going "mainstream at the metropole" (Silverstein 2015: 7). Attention to multilingualism in Indigenous contexts tends to focus exclusively on the dynamics between local languages on the one hand and new languages that grow or come into being as a result of colonialism on the other, such as English, Portuguese, Nheengatú or Australian Kriol. In some regions there has been early and continuing attention to Indigenous multilingualism, such as in Americanist work on pre-contact cross-language dynamics, established in the Boasian tradition of anthropological linguistics (Kroskrity, Epps). However, in general there has been a lack of attention to relations between Indigenous languages. These dynamics can be overshadowed by a focus on colonial-Indigenous relations or rendered invisible by assumptions about traditional life informed by linguistic nationalism. As the papers in this special issue show, intra-Indigenous multilingualisms are an integral part of intra-Indigenous relations more generally, and distinct from colonial-Indigenous relations. For example, Epps notes that while code-switching between Hup and Portuguese is common, code-switching between Hup and another Indigenous language would evoke strong censure (cf. Vaughan in press). The papers in this issue contextualise Indigenous multilingualisms, revealing the ways that multiple Indigenous languages come to be deeply embedded into the fabric of daily life. Some reflect on the effects of linguistic work on local language ideologies, such as classifications of Indigenous languages and the valorisation of certain Indigenous languages by missionaries or governments (Narayanan, Vaughan). The papers in this issue compare observations about contemporary multilingualism with records of multilingualism from earlier contact eras and reconstructions of pre-contact patterns of language use. Intensely multilingual ecologies have been reported at various times and places within the present-day United States, Australia, South America, Melanesia, and West Africa. Many of the Indigenous communities where multilingualism has endured are at global 'peripheries'; the edges of imperial, colonial and globalizing projects (May 2016; Pietikäinen & Kelly-Holmes 2013; Silverstein 2015). In researching Indigenous multilingualisms, it has typically been a challenge for researchers to 'un...