This book investigates two prominent issues with regard to the inflected infinitive - the syntactic distribution of the Portuguese inflected infinitive, and its origin and development from Early Romance. The Syntactic analysis offered here differs from traditional descriptions of the inflected infinitive in that it uses a theoretical approach to propose on concise condition which predicts all possible occurences of the Portuguese inflected infinitive within the framework of relational grammar.This study presents a detailed comparison of the syntactic environments common to both the imperfect subjunctive and the inflected infinitive, and examines the survival of an inflected infinitive in other Romance varieties as well as the existence of other inflected non-finite forms in these languages.