The general goal of this dissertation is to highlight the role of discourse pragmatics in the explanation of the use of the indicative and subjunctive moods in Spanish sentential complements. This dissertation examines mood selection in Spanish complements in order to illustrate the shortcomings of the traditional semantic/syntactic approach (Terrell & Hooper (1974), Hooper (1975), P. Klein (1974), Fukushima (1978-79), Bell (1980), and Takagaki (1984)) and to provide within the Information Structure framework (Lambrecht 1994; 2001) a detailed analysis of mood selection in Spanish complement clauses. Considering some existing pragmatic approaches to Spanish mood selection (e.g., Lavandera 1983, Guitart 1991, Mejías-Bikandi 1994, 1998), they are found to be inadequate because they are based on decontextualized sentences. This dissertation considers the context where sentences take place and contributes to our understanding of mood selection in Spanish complements as a formal reflection of the pragmatic properties and relations of the discourse referents that are denoted by noun complements, considering pragmatic notions of presupposition and assertion of propositional referents, their activation, and the pragmatic relations of topic/focus of these referents in the utterances. The notion of pragmatic assertion used in this dissertation is based on the notion of speaker intent, and it is equated with the notion of inactive discourse referents, which are in turn linked to the use of indicative mood in complements of assertive matrices. The notion of pragmatic presupposition is equated with the notion of active referents in the discourse, which are in turn linked to the use of subjunctive mood in complements of doubt/negation and comment matrices. However, this thesis argues that not all uses of subjunctive are motivated by the active status of propositional referents. Volitional and possibility uses of subjunctive are analyzed, similarly to assertive matrices, as activating a discourse referent. Yet, contrary to assertive matrices, and following Fauconnier’s (1985) theory of mental spaces, the referent activated belongs to the domain that represents an individual’s view of reality. This account of mood distribution in complement clauses is eventually extended to adjectival and adverbial subordinates and provides an explanation of mood distribution in all subordinate contexts in Spanish. / text