The first book to place complex interventions within a coherent system of research enquiry, this work is designed to help researchers understand the research processes involved at each stage of developing, testing, evaluating and implementing complex interventions, and assist them to integrate methodological activities to produce secure, evidence-based health care interventions. It begins with conceptual chapters which set out the complex interventions framework, discuss the interrelation between knowledge development and evidence, and explore how mixed methods research contributes to improved health. Structured around the influential UK Medical Research Council guidance for use of complex interventions, four sections, each comprised of bite-sized chapters written by multidisciplinary experts in the area, focus on: - Developing complex interventions - Assessing the feasibility of complex interventions and piloting them - Evaluating complex interventions - Implementing complex interventions. Accessible to students and researchers grappling with complex interventions, each substantive chapter includes an introduction, bulleted learning objectives, clinical examples, a summary and further reading. The perspectives of various stakeholders, including patients, families and professionals, are discussed throughout as are the economic and ethical implications of methods. A vital companion for health research, this book is suitable for readers from multidisciplinary disciplines such as medical, nursing, public health, health services research, human services and allied healthcare backgrounds.