The present volume is based on the proceedings of the Advanced Study Institute (ASI) sponsored by the North Atlantic Treaty Organization (NATO). The Institute was conducted at the beautiful Chateau de Bonas near Toulouse France in October 1991. A number of scholars from different countries participated in the two-week institute on differential diagnosis and treatments of reading and writing problems. The accepted papers for this volume are divided into three sections: (a) Differential diagnosis of reading disabilities; (b) Access to language-related component processes; and (c) Reading/spelling strategies. The other papers appear in a companion volume: Developmental and Acquired Dyslexia: Neuropsychological and Neurolinguistic Perspectives also coedited by Joshi and Leong and published by Kluwer Academic Publishers. Several people and organizations have helped us in this endeavor and their assistance is gratefully acknowledged. Our special thanks are due to: the Scientific Affairs Division of NATO for providing the major portion of the financial support; Dr. L. V. da Cunha of NATO and Dr. THo Kester and Mrs. Barbara Kester of the International Transfer of Science and Technology (ITST) for their help and support of the various aspects of the institute; Mr. Charles Stockman and the entire staff of the Chateau de Bonas for making our stay a pleasant one by helping us to run the Institute smoothly. We also wish to thank our reviewers and the following people for other assistance: Christi Martin and Xi-wu Fang.