This publication is part of the Substance Abuse Prevention and Treatment Block Grant technical assistance program. All material appearing in this volume except quoted passages from copyrighted sources is in the public domain and may be reproduced or copied without permission from the Center for Substance Abuse Treatment (CSAT) or the authors. Citation of the source is appreciated. This publication was prepared under contract number 270-93-0004 from the Substance Abuse and Mental Health Services Administration (SAMHSA). Gayle Saunders, of CSAT, served as the Government project officer. The opinions expressed herein are the views of the authors and do not necessarily reflect the official position of CSAT or any other part of the U.S. Department of Health and Human Services (DHHS).