Single-case research has played an important role in developing and evaluating interventions that are designed to alter a particular facet of human functioning. Now thoroughly updated in its second edition, acclaimed author Alan Kazdin's Single-Case Research Designs provides a notable contrast to the quantitative methodology approach that pervades the biological and social sciences. While focusing on widely applicable methodologies for evaluating interventions--such as treatment or psychotherapy using applied behavior analysis--this revised edition also encompasses a broader range of research areas that utilize single-case designs, demonstrating the pertinence of this methodology in various disciplines, from psychology and medicine to business and industry. This well-written, clear, and thoroughly updated text is ideal for practitioners, instructors, and students alike.