This volume brings together studies in the domain of weak referentiality, the phenomenon that a definite or indefinite noun phrase lacks its usual referential force. Several papers investigate syntactic or semantic properties of indefinite noun phrases, such as modality, number neutrality, narrow scope, incorporation, predication, and case marking, and that in a range of languages (Arabic, Brazilian Portuguese, Catalan, German, Papiamentu, Russian). Other papers deal with weakly referential definite noun phrases in various languages (Basque, Dutch, English, French) involving scrambling, modification, possession, and accessibility. The papers demonstrate a range of empirical methods and theoretical models. This volume will not only be of interest to researchers and students in syntax and semantics, but also in psycholinguistics and language typology.