© John Benjamins Publishing Company. In this introduction, we set out the central themes of the special issue. It concentrates on imperfect function-form mappings, and discusses several cases in which specific perspectival meanings are not fully predictable on the basis of a perspectivizing grammatical construction alone. We distinguish two kinds of form-function mismatches: (1) perspective-persistent phenomena, i.e. grammatically signaled deictic and/or cognitive perspective shifts which are not realized in interpretation, and (2) irregular perspective shifts, which involve either grammatically un(der)specified shifts or grammatically signaled shifts that are interpreted as mixing multiple sources of deictic and/or cognitive perspective (‘...