Written to be accessible to students and practitioners as well as researchers, this handbook is a uniquely ambitious work that will alter both theoretical and applied landscapes. It surveys a field that has grown dramatically over the past forty years, since sign languages were first recognized by scientists to be true languages. From work on the linguistics of sign language and parent-child interactions to analyses of school placement and the mapping of brain function in deaf individuals, research across a wide range of disciplines has greatly expanded not just our knowledge of deafness and the deaf, but of the very origins of language, social interaction, and thinking. Bringing together historical information, research, and strategies for teaching and service provision, Marschark and Spencer have given us what is certain to become the benchmark reference in the field.