The development of functional categories has been the topic of intense research in the past decade in each of the acquisition domains, to the extent that acquisition of functional categories has become the dominant line of enquiry in the research on syntactic development in the generative framework. This volume aims to bring together generative research on the nature of the grammars developed by French learners in different acquisition contexts, namely first language acquisition, second language acquisition, bilingual first language acquisition and specifically-language impaired acquisition.