This book is written for student researchers, practitioners, and university faculty who are interested in answering applied research questions and objectively evaluating educational and clinical practices. The basic tenet of single-subject research methodology is that the individual is of primary importance and that each individual study participant serves as his or her own control. It is because of this focus on the individual that clinicians and educators have been using single-subject research designs for over 40 years to answer applied research questions. Although the methodology has its roots in behavioral psychology and applied behavioral analysis, it has been used by applied researchers across a variety of disciplines such as special education, speech and communication sciences, language and literacy, therapeutic recreation, occupational therapy, and social work. Key features include the following: