Any theory of phonology must be able to account for the acquisition and development of a phonological system, and studying acquisition often leads to reciprocal advances in the theory. This volume explores the link between phonological theory and linguistic development from a variety of angles, including phonological representation, individual differences, and cross-linguistic approaches. Chapters touch on the full spectrum of phonological development, from childhood to adult second-language learning, and from developing dialects to language death. Contributors are leading researchers in the fields of linguistics, speech pathology, and cognitive psychology. A tribute to Daniel A. Dinnsen, the papers in this volume complement his research career by highlighting significant contributions of acquisition research to the development of phonological theory.