This book represents the state of the art in the study of gradience in grammar: the degree to which utterances are acceptable or grammatical, and the relationship between acceptability and grammaticality. Part I seeks to clarify the nature of gradience from the perspectives of phonology, generative syntax, psycholinguistics, and sociolinguistics. Parts II and III examine issues in phonology and syntax. Part IV considers long movement from different methodological perspectives. The data discussed comes from a wide range of languages and dialects, and includes tone and stress patterns, word order variation, and question formation. The book will interest linguists concerned with the understanding of syntax, phonology, language variation and acquisition, discourse, and the operations of language within the mind.