Mixed languages are a type of contact language that results from two or more languages combining in a situation of multilingualism. They arise during times of significant social change, serving as an expression of a new identity or the maintenance of an older identity. This chapter overviews languages which have been classified as “mixed languages” (§2) and presents case studies of a number of these languages within a typological classification: (i) Lexicon-Grammar (LG) mixed languages, where one language provides the grammar and another language contributes large amounts of vocabulary; (ii) structural mixes, where both languages contribute significant amounts of grammatical (and lexical) material to the new language; and (iii) converted languages, where a language maintains its lexicon but undergoes structural convergence with another language (§3). The chapter then discusses their contemporary functions (§4.1), their socio-historical origins (§4.2), and the linguistic processes (§5) that led to their genesis. Section 6 provides the first detailed discussion of the phonology of the mixed languages. As will be shown, the mixed languages originate from a range of socio-historical settings and linguistic processes that do not obviously predict the resultant shape of the language.