A long awaited magnum opus from a leading figure in the interdisciplinary study of language. Humans naturally acquire languages that connect meanings with pronunciations. Paul M. Pietroski presents an account of these distinctive languages as generative procedures that respect substantive constraints. According to Pietroski, meanings are neither concepts nor extensions, and sentences do not have truth conditions. He argues that meanings are composable instructions for how to access and assemble concepts of a special sort.