In contrast to other helping professions, social work does not currently define itself as scientific, or as a scientific discipline. Starting with the work of John Brekke, this volume considers what a science of social work might look like. These ideas have developed from an extended collaboration among the chapter authors and others. Aspects of the framework described here include approaches to ontology and epistemology (scientific and critical realism); science and the the identity of social work; the context of Grand Challenges for social work; the place of values in a science of social work; the importance of theory in social work science; and how ideas from the philosophy of mind can also inform what a social work science should be. The volume then describes the application of social work science to social work practice, managing the tensions between rigor and relevance, and ways to educate future scholars. The concluding chapter suggests some ways in which this framework might affect social work practice and education in the future.