This dissertation is an attempt to characterize the notion "exception to a rule of grammar" within the context of Chomsky's conception of grammar as given in "Aspects of the Theory of Syntax." This notion depends on a prior notion of "rule government"--in each phrase marker on which a transformational rule may operate, there exists one lexical item which governs that rule. Only that item may be an exception to the rule. There are two types of transformational rules--(1) major, which apply in normal cases, but do not apply to exceptions, and (2) minor, which apply only to cases" but do not apply to exceptions, and (2) minor, which apply only to exceptions, but do not apply in normal cases. These are "simple exceptions." In addition, there are "absolute exceptions," lexical items which must, or must not, meet the structural description of some transformational rule. It is assumed in this work that each lexical item is subcategorized with respect to each transformational rule and each structural description. These categories are termed "rule features" and "structural description features." Some lexical items must be represented with Boolean functions of these features. Thus, each grammar may be said to define the set of possible exceptions to its rules. (Author/AMM)