As a division of the School of Medicine at the University of North Carolina at ChapeI Hili, TEACCH has always been involved in the latest biological research on autism and related developmental disabilities. However, until now there has not been sufficient information to justify aseparate volume on this most important topic. Recent advances both in our understanding of the brain and in the technology to facilitate the measurement of neurological functioning have stimulated significant growth, which is reflected in this volume. As with the preceding books in this series, Current Issues in Autism, this volume is based on one of the annual TEACCH conferences held in ChapeI Hili each May. The books are not simply published proceedings of the conference papers, however. lnstead, conference participants are asked to develop chapters around their presentations, and other international experts whose work is beyond the scope of the conference, but related to the major theme, are asked to contribute as weil. These volumes are intended to provide the most current knowledge and professional practice available to us concerning major issues in autism.