This chapter explicates the Role and Reference Grammar (RRG) theory of case assignment and outlines its OT implementation and its extension to instrumental case assignment and case syncretism. The ’non-OT’ theory of case assignment in RRG is a version of dependent case theory that assigns nominative, accusative, absolutive and ergative case in terms of the ranking of actor and undergoer, while its OT-based counterpart defines accusative, ergative, dative and instrumental case with reference to (non-)macrorole status, conflates nominative and absolutive as an any-argument case, and derives the variation of case syncretism from the case hierarchy of Silverstein (1980/1993).

Chapter 1 is devoted to an introduction into the topic of case in general and its relation to semantics in particular. It illustrates a range of case alternations in different languages, showing, on the intuitive level, the ways in which the form of the noun affects sentential meaning. The inherently relational nature of case is discussed, and the distinction is made between abstract, morphological and morpho-syntactic case. The chapter further addresses the classification of cases into structural/configurational, inherent, lexical and semantic. Examples of several case systems in different languages of the world are provided, and the distinction between ergative-absolutive and nominative-accusative languages is introduced. The chapter also briefly illustrates the interrelation between case-marking and theta-role assignment, a phenomenon that is familiar primarily from the literature on inherent case. Finally, the structure of the following chapters is outlined.