Only recently has linguistic research recognized sign languages as legitimate human languages with properties analogous to those cataloged for French or Navajo, for example. There are many different sign languages, which can be analyzed on a variety of levels—phonetics, phonology, morphology, syntax, and semantics—in the same way as spoken languages. Yet the recognition that not all of the principles established for spoken languages hold for sign languages has made sign languages a crucial testing ground for linguistic theory.

Edited by Susan Fischer and Patricia Siple, this collection is divided into four sections, reflecting the traditional core areas of phonology, morphology, syntax, and semantics. Although most of the contributions consider American Sign Language (ASL), five treat sign languages unrelated to ASL, offering valuable perspectives on sign universals. Since some of these languages or systems are only recently established, they provide a window onto the evolution and growth of sign languages.

The recent recognition of sign languages as legitimate human languages has opened up new and unique ways for both theoretical and applied psycholinguistics and language acquisition have begun to demonstrate the universality of language acquisition, comprehension, and production processes across a wide variety of modes of communication. As a result, many language practitioners, teachers, and clinicians have begun to examine the role of sign language in the education of the deaf as well as in language intervention for atypical, language-delayed populations.

This collection, edited by Patricia Siple and Susan D. Fischer, brings together theoretically important contributions from both basic research and applied settings. The studies include native sign language acquisition; acquisition and processing of sign language through a single mode under widely varying conditions; acquisition and processing of bimodal (speech and sign) input; and the use of sign language with atypical, autistic, and mentally retarded groups.

All the chapters in this collection of state-of-the-art research address one or more issues related to universality of language processes, language plasticity, and the relative contributions of biology and input to language acquisition and use.