Prosodic morphology concerns the interaction of morphological and phonological determinants of linguistic form and the degree to which one determines the other. This is the first book devoted to understanding the definition and operation of canonical forms - the invariant syllabic shapes of morphemes - which are the defining characteristic of prosodic morphology. Dr Downing discusses past research in the field and provides a critical evaluation of the current leading theory which, she shows, is empirically inadequate. She sets out an alternative approach and tests this in a cross-linguistic analysis of phonological and morphological forms over a wide range languages, including several not previously been studied from this perspective. Prosodic morphology has been the testing ground for theoeretical developments in phonology over the past twenty years, from autosegmental theory to optimality theory. This book will be of central interest to specialists in phonology and morphology, as well as to advanced students of these fields and of linguistic theory more generally.