This research is framed in the context of recent developments in linguistic theory and second language acquisition theory. It examines French second language learners' interlanguages within the framework of Universal Grammar (UG). The study is a cross-sectional study of English speaking learners of L2 French in a classroom setting: from the early stages of acquisition to learners studying for a degree. The aim was to carry out a precise study of their interlanguage grammars at various points of acquisition. Through implementation of a battery of tests the study focused on the subjects' knowledge of negation, the placement of phrase medial adverbs, lexical verbs inversion, and object pronoun placement. The objective was to investigate the availability and development of functional categories and their features from the initial state through subsequent stages of development; in particular those functional categories implicated in the verb movement parameter and the object pronoun placement parameter. The results are used to evaluate current theoretical positions on the L2 initial state and also the various hypotheses concerned with the status of functional categories and their feature values as interlanguages develop. A crucial factor for any theory of language acquisition is the role of input, and significantly this study also investigated the link between the learners' representations and the input that was available to them. A period of observation was set up in an attempt to establish the nature of the input for these learners and how it may effect or affect their interlanguage grammars.