This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book is concerned with the utility of single-case evaluation in social work, and the experience of applying this methodology in practice. It demonstrates the viability of single-case designs as a research method in addressing particular questions of evaluation in social work practice. The book describes a similar project with students on placement with West Yorkshire Probation Service. It focuses on the experience of applying this methodology in combination with other methods to evaluate the effectiveness of community care projects for older people. The book draws on the experience of social workers in a number of settings and agencies in Britain to assess the utility of this methodology in practice. A literature search in the late 1980s indicated that there was an evaluation research methodology which claimed to offer appropriate strategies for social workers seeking to evaluate their practice with service users.