Rules in this study are limited to linguistic entities which are said to have truth value, to be followable and prescriptive, to have been adopted and remain in force until unadopted, and to be conditional. The concern is with the nominal referential use of rules rather than their verbal use. The book is divided into four sections. The first examines rules and descriptions; the second examines the relation of rules to games; the third contrasts rules with scientific laws; and the fourth section relates rules to the native speaker. Three appendices are provided, i.e., Everyday Confusions, Some Questions for Behaviorists, and To What Does "Rule" Always Refer? (HS)