This book combines research and perspectives from anthropology, sociology, applied linguistics, developmental psychology and neurobiology to argue for a theory of language acquisition via enculturation. The first part of the book examines the practices by which we are enculturated. Indeed, members of a society are socialized into their culture, and more specifically to use language through language via processes that include eavesdropping, observation, participation, imitation, and language socialization. However, ethnographic accounts also overwhelmingly show that children become enculturated in large part on their own initiative. The second part of the book argues for a motivation to attune to, seek out, and become like others-or an 'interactional instinct', which facilitates enculturation and the biology that subserves it. The closing chapters explore more of our biological readiness and the neurological structures and systems that may have evolved to respond to the input provided by society to facilitate the learning of cultural practices and traditions by its youth. The picture that emerges indicates that biology is nature and culture is nurture, but there is no nurture without nature, and it is nurture that provides for the phylogenetic development of our biological nature. The ontogenesis of language behavior, i.e. its acquisition, cannot occur without its evolved biology or without its evolved cultural practices for socialization.