This book examines argumental un-NPs and du/des-NPs in French: nominals with the indefinite article and with the so-called 'partitive article' respectively. The main aim is to account for the different interpretations of these indefinites and to determine how interpretation and structure are related. This study thus concerns the syntax-semantics interface, with an emphasis on the composition of the left periphery and the inflectional domain of the indefinites mentioned. It is realized in the framework of generative grammar and in a cartographic approach. A crucial proposal put forward in this book is that indefinites of different semantic types are associated with different left peripheries. The analysis further suggests that the inflectional domain of these indefinites may comprise three discrete functional projections encoding the features [count], [quantity] and [number]. Interestingly, these results seem to extend to a selection of bare nouns in Romance and Germanic languages.