This thesis proposes an integration of Paradigm Function Morphology (PFM) as the morphological component within the Lexical-Functional Grammar (LFG) architecture, applying the combined theoretical framework LFG-PFM to account for diachronic data. The theory is developed by application to two case studies from Portuguese involving mismatches between different levels of grammatical structure and resulting in divergence between varieties of the language. In each case, I give a new presentation of the Portuguese phenomena, which have not previously been treated in LFG or PFM.








