Behavior modification is one of the leading psychological approaches to current work on mental health. The strength of behavior modification derives partly from its scientific grounding and the empirical validation of its procedures, and partly from its humane application of psychological principles to a wide diversity of clients. Current behavior modification is a heterogeneous area of research and application. This article highlights present directions of research and practice in behavior modificacion. Topics addressed include concept and characteristics, approaches, theory, efficacy, effectiveness and efficiency, the role of treatment manuals, assessment, techniques and clinical practice, and applications.