The chapter introduces the concept of Optimality Theory in generative grammar, emphasizing the interaction of constraints and the selection of optimal outputs. The authors, Alan Prince and Paul Smolensky, argue that grammatical processes often involve selecting the optimal output from among a set of possibilities, where "optimal" is defined in terms of the constraints bearing on the grammatical domain. They illustrate this with the example of syllabification in Imdlawn Tashlhiyt Berber, where the selection of syllable nuclei is determined by the relative sonority of the elements in the string. The chapter also introduces the notion of constraint domination and the mechanism for computing optimality with respect to a set of prioritized constraints. The authors demonstrate how this approach can resolve issues such as triggering and blocking, and provide a formal characterization of evaluation with respect to a constraint hierarchy. The chapter concludes by discussing the implications of Optimality Theory for the study of syllable structure and prosodic-morphological processes.The chapter introduces the concept of Optimality Theory in generative grammar, emphasizing the interaction of constraints and the selection of optimal outputs. The authors, Alan Prince and Paul Smolensky, argue that grammatical processes often involve selecting the optimal output from among a set of possibilities, where "optimal" is defined in terms of the constraints bearing on the grammatical domain. They illustrate this with the example of syllabification in Imdlawn Tashlhiyt Berber, where the selection of syllable nuclei is determined by the relative sonority of the elements in the string. The chapter also introduces the notion of constraint domination and the mechanism for computing optimality with respect to a set of prioritized constraints. The authors demonstrate how this approach can resolve issues such as triggering and blocking, and provide a formal characterization of evaluation with respect to a constraint hierarchy. The chapter concludes by discussing the implications of Optimality Theory for the study of syllable structure and prosodic-morphological processes.