This volume brings together new research on theoretical Romance Linguistics; its intended audience is scholars in the field of formal grammar, especially those specializing in Romance languages. It represents the latest work on the structure of Romance languages, with relevant comparisons to other languages such as English and Basque. As the volume's title indicates, two related themes recur in these studies: the role of grammatical features in sub-modules of the grammar, and the interaction of sub-modules with each other and with external systems at the "interfaces". The contributions to this volume, all framed within current theoretical models, explore these and related problems in the analysis of Romance. The volume contains studies on morphology, phonology, syntax and semantics, and includes language and subject indices.