First published in 1990, this dissertation presents an event-based model-theoretic semantics for plural expressions in English. The author defends against counterarguments the hypothesis that distributive predicates are predicates of groups, and not just individuals. By defining the collective/distributive distinction in terms of event structure, he solves formal problems with previous group-level analyses. The author notes that certain adverbials have a systematic ambiguity between a reading indicating collective action, and readings indicating spatial or temporal proximity; the event-based definition of collective action makes possible a parallel treatment of these readings. This book presents a formal proposal on the algebraic structure of groups and events, and a semantically based analysis of number agreement.