A new contribution to linguistic theory, this book presents a formal framework for the analysis of word structure in human language. It sets forth the network of hypotheses constituting Paradigm Function Morphology, a theory of inflectional form. The book differs from other recent works on the same subject in that it treats inflectional morphology as an autonomous system of principles rather than as a subsystem of syntax or phonology and it draws on evidence from a diverse range of languages in motivating the proposed conception of word structure.