This thesis presents a phrase structure account of a particular class of English noun phrases; partitives. Constructions which are directly related, notably pseudopartitives, are also analysed, and the proposals have implications for the representation of simple noun phrases. The main aim is to provide a concise and explicit account of the data and to this end the syntactic rules are presented in a computer-usable form. The background to the analysis is provided by reviewing a number of seminal accounts of noun phrase structure, and there is also a review of some research on the semantics of noun phrases which directly bears on the work presnted here. In the absence of a semantic theory which captures all the relevant facts, some requirements are stated and some directions indicated. This thesis makes a number of specific claims, among which are the following: * Partitive noun phrases are minimally distinct from simple and pseudopartitive noun phrases syntactically and semantically. * Genitive partitive noun phrases in Old English and in languages such as modern German and Polish are closely related to the modern English partitive form. * The partitive definiteness constraint must be reformulated. * The phenomena of definiteness should be treated in a theory which allows interaction with the domain of discourse. The main contribution of the thesis is in the provision of a precise, practical, and theoretically motivated grammar of English noun phrases which aims to generate, as nearly as possible, 'all and only' the required strings of the language.