Computational phonology is one of the newest areas of computational linguistics, and is experiencing rapid growth as its practitioners apply the wealth of theories, technologies and methodologies of computational linguistics to phonology. This book is the first to survey these developments, and it does so in a way that is accessible to computational linguists, phonologists and computer scientists alike. The interests of these diverse groups overlap in the subject area of constraints. The goal of this book is to explore the use of constraints in modern non-linear phonology and then - drawing on insights from constraint-based grammar and constraint logic programming - to formalise and implement a constraint-based phonology.