Routledge Handbook of Sedentary Behaviour assesses the field and provides an in-depth update on sedentary behaviour research. Sedentary behaviour is defined as any waking behaviour where the energy expenditure is low and the predominant posture is sitting, reclining, or lying. Evidence is rapidly accumulating that sedentary behaviour is associated with poor health outcomes. Over the past 20 years, time spent sitting has increased dramatically as people spend more time sitting for work, commuting, and leisure. Excessive sedentary behaviour has been associated with an increased risk of numerous noncommunicable diseases. The field of sedentary behaviour research is rapidly developing. This book provides a source of information on the epidemiological trends in sedentary behaviour across the life course. Innovations in quantifying sedentary behaviour have led to a number of developments in tools used to measure sedentary behaviour, and this book reviews their relative merits. Our understanding of the range of physical and mental health effects continues to expand, and these are discussed, including likely causal mechanisms. Following this, the effectiveness of various interventions within different populations is presented. Finally, the text summarises these advances in knowledge and gives direction to new areas for future research. The text offers students, researchers, and academics an up-to-date summary of the sedentary behaviour evidence base and serves as a catalyst for future research through summaries of future research areas that remain addressed.