This introductory chapter reviews how researchers across a range of disciplines have critically reassessed their conceptions of language and of the relationship between language and identity, especially in multilingual or superdiverse contexts. Key elements of the ‘multilingual turn’ are elaborated, including the focus on the construction and negotiation of identity and the view of languages as part of a multimodal repertoire, thereby broadening and problematizing the definition of multilingualism. In a second section, the terminology used to describe multilingual speakers and practices is analysed, and its relation to the values and identities ascribed to them is assessed. The chapter then presents the three major themes around which the volume is structured: situated multilingualism and identity, multilingual identity practices and multilingual identity and investment. The final section explores the extent to which interdisciplinarity is represented both within the chapters and across the volume, and how far ‘integration’ and ‘common ground’, considered key aims for successful interdisciplinary work, have been possible.