Abstract
This chapter reviews 50 years of literature on switch-reference (SR), a grammatical phenomenon found in more than 70 North American languages and at least six South American families, in which one clause is morphologically marked to show whether its subject refers to the same entity or entities as the subject of a structurally nearby clause. Our review is organized around three central issues: to what extent is SR a semantic phenomenon or a syntactic phenomenon, what sorts of clauses can be marked for SR, and what counts as a subject for purposes of SR marking. We also briefly point out some similarities and differences between SR and some other reference-tracking devices found in American languages.