This book makes a fundamental contribution to phonology, linguistic typology, and the nature of the human language faculty. Distinctive features in phonology distinguish one meaningful sound from another. Since the mid-twentieth century they have been seen as a set characterizing all possible phonological distinctions and as an integral part of Universal Grammar, the innate language faculty underlying successive versions of Chomskyan generative theory. The usefulness of distinctive features in phonological analysis is uncontroversial, but the supposition that features are innate and universal rather than learned and language-specific has never, until now, been systematically tested. In his pioneering account Jeff Mielke presents the results of a crosslinguistic survey of natural classes of distinctive features covering almost six hundred of the world's languages drawn from a variety of different families.