This book develops a unified account of expressions involving the notions of "part" and "whole" in which principles of the individuation of part structures play a central role. Moltmann presents a range of new empirical generalizations with data from English and a variety of other languages involving plurals, mass nouns, adnominal and adverbial modifiers such as as a whole, together, and alone, nominal and adverbial quantifiers ranging over parts, and expressions of completion such as completely and partly. She develops a new theory of part structures which differs from traditional mereological theories in that the notion of an integrated whole plays a central role and in that the part structure of an entity is allowed to vary across different situations, perspectives, and dimensions.