Book excerpt: This book studies the syntax of switch-reference and its implications for the theory of grammar. Switch-reference, found in many genetically and geographically diverse languages, is a phenomenon whereby referential identity between subjects of hierarchically adjacent clauses is encoded by the presence of a morpheme, usually suffixed to the verb of the subordinate clause. This book argues that switch-reference should be analysed as a syntactic rather than a purely pragmatic or functional feature of language.