This study provides a new approach to Spanish clitic doubling, basing the analysis of these constructions on spontaneous data considered within their broad discourse context. This type of analysis appeals to cognitive and pragmatic categories, and advances an explicit comparison between the Argentine, Mexican and Spanish regional variants of the language. This method embraces the graduality and heterogeneity that emerge from natural data, particularly in regard to a phenomenon that represents a change in progress at different stages in the different varieties. It demonstrates that the principle that best captures the conditions governing doubling constructions is the cognitive accessibility assumed of the target referent in the mind of the interlocutor. It distinguishes different subtypes of "doubling," which are taken to represent a variety of points along a continuum of grammaticalization of discourse strategies, with the discourse relation between an anaphor and its antecedent at one end and prototypical grammatical agreement at the other. These different degrees of grammaticalization are apparent when examining the morphophonological and morphosyntactic behavior of dative and accusative clitics in each dialect, and they correlate with the subtypes of "doubling" that are most common in each one. In addition, the book concludes with an examination of these constructions in Role and Reference Grammar, a model that allows the interplay of syntax, semantics and pragmatics evidenced by clitic doubling to be naturally accounted for, and provides a formalization of these structures consistent with the diversity of naturally-occurring data.