Why is there a volume in Comprehensive Clinical Psychology specifically tilled Research and Methods when much of ihe material in the other volumes draws on the research base of the field? The Hdiiors-in-Chief believe that the value of research to the field justifies the prominence of a volume that directly addresses research methodologies rather than allowing readers to recognize the importance of research by reading of its results in all the volumes of this series. Volume 3 builds on Volume I. Foundations, which provides the linkage of clinical psychology to other fields in psychology and other behavioral sciences. The present volume addresses research methods and areas that are core to clinical psychology but also attempts to go beyond the traditional boundaries of the field by introducing methods and techniques that historically have not been core to the field. Clinical psychological research today utilizes a broad array of methods that have evolved from simple description and use of correlational approaches to complex experimental designs and statistical techniques.