This book proposes a new theory of the grammaticalization of articles and noun phrase structure. While most work in grammaticalization theory has focused on grammaticalizing elements, here the grammatical construction (NP) into which a grammaticalizing element (article) enters is of central concern. A rigorous and comprehensive account is given of the closely correlated development on both the element and the constructional levels is provided, addressing semantic, pragmatic, and syntactic issues. Apart from definite and specific articles, a broad variety of constructions involving articles is discussed (e.g. linking articles), and a new typology for articles is proposed. It is shown that this broad variety of article constructions derives from a single universal use of demonstratives.