This volume is an excellent introduction to the principles and workings of optimality theory, arelatively new constraint-based framework. The focus is on phonology, which is where the theorythus far has had its greatest impact. A basic understanding of phonology and earlier rule-basedderivational theories is assumed. At appropriate points, Kager distinguishes the different claimsmade by optimality theory and derivational theories. The exercises and suggested readings at theend of each chapter make the book highly suitable as a textbook. The conclusion of each chapteralso provides a good summary of the main points. In addition to conventional subject andlanguage indexes, a helpful index of constraints is included with page numbers for where theconstraint is defined and used.