This textbook provides a grounding in complexity theory, demonstrating how it can influence and shape social work interventions in policy, management, and practice, as well as forming an epistemological and methodological basis for research. It provides a contemporary theoretical basis for social work practice, equipping social workers to work in a 21st-Century world.  The authors argue that the history of social work demonstrates the professions engagement with the social and structural problems of each era since its emergence 150 years ago. However, in  the 21st Century, such things as globalisation, the COVID-19 pandemic, and climate change have highlighted that existing theories and practice models are insufficient to the task of working with the complicatedness of contemporary life in a fast-changing world. Distilling the central tenets of Complexity Theory and the notion of complex adaptive systems in partnership with pragmatism, the book provides practice perspectives and guidelines which build on social works enduring commitment to understanding the person-in-context. The recognition that social workers require conceptual and theoretical agility to work across micro, meso and macro levels remains central, but the argument is made that their focus and practice must primarily be at the meso level. The authorship of combined academic and practice expertise enables such perspectives to be brought to life through the theoretical and practical analysis of conceptual and real-world challenges.  The book consists of 13 chapters organized in three sections: Part I: Complex Practice in a Complex World Part II: Thinking Complexity in Practice Part III: Thinking Complexity in Public Policy, Research and Education Complexity Theory for Social Work Practice encourages social workers to think complexity and act pragmatically. It is intended for final-year social work students; academics and researchers working in a range of disciplines, primarily in the social work field but also in the areas of sociology, psychology and anthropology; and practitioners in policy, research, management and practice settings.