This study provides a consistent description and explanation of the syntax, the semantics and the pragmatics of Spanish mood. A major focus of attention is the central role of the truthfunctional categories of realis, potentialis and irrealis as parameters relevant to mood selection in both subordinate and non-subordinate clauses. Furthermore, a proposal is offered for a new typology of clause-embedding predicates. The framework chosen stems from the insight that complement-taking predicates share the property of providing information on the set of mental processes which characterize intentional human behaviour. At the level of pragmatic analysis, mood selection is examined from a variety of angles. Thus, specific research is conducted within the framework of speech act theory, relevance theory, politeness theory and the theory of Gricean maxims.