Questions of responsibility arise at all levels of health care. Most prominent has been the issue of patient responsibility. Some health conditions that risk death or serious harm are partly the result of lifestyle behaviours such as smoking, lack of exercise, or extreme sports. Are patients with such conditions responsible for them? If so, might healthcare providers, be they state-run systems or private entities, be justified in treating such patients differently? And if they are, which forms of differential treatment are justified? Responsibility isn’t just relevant for patients. Even when individuals affect their health through voluntary behaviour, other influences are also at work before, during, and after the patient’s interaction with the health care system. What are the responsibilities of individual clinicians and other medical professionals, when thinking about individual and public health? What about institutions such as governments or national health care services, or society as a whole? This collection brings together work by world-renowned experts in population ethics, distributive justice, philosophy of action, cognitive science, and medical ethics in order to push the debate forward by elucidating our understanding of these questions, their possible answers, and how they are related.