In this monograph, various aspects of the morphosyntactic evolution of the Romance languages are shown to interact in a theory of grammaticalization. The study argues for the incorporation and subordination of inflectional morphology within a grammaticalization continuum, constituting but a portion of the latter. Parameters of natural morphology are seen as principles of grammaticalization, but the reverse is also true, rendering grammaticalization and natural morphology indistinguishable. In the context of this theoretical framework, Chapter 2 deals with Latin, French, and Italian verbal inflection, focusing on universal and system-dependent parameters of natural morphology. In Chapter 3, a theory of grammaticalization is built on divergent elements, including not only grammaticalization studies proper, but also the perception/production line of inquiry, and typology and branching issues, permitting the phasing out of the traditional synthesis/analyis cycle. Chapter 4 touches on nominal inflection, in particular that of Old French and Rumanian, the most revealing histories in the Romance domain. Chapter 5, finally, thoroughly discusses extant theoretical questions in grammaticalization, prominently featuring the relevance of ‘invisible hand’ explanations and the crucial role played by unidirectionality. This study will be of interest to specialists in Romance and historical linguistics, as well as morphological theory.