Combatting chronic, lifestyle-related disease has become a healthcare priority in the developed world. The role personal responsibility should play in healthcare provision has growing pertinence given the growing significance of individual lifestyle choices for health. Media reporting focussing on the ‘bad behaviour’ of individuals suffering lifestyle-related disease, and policies aimed at encouraging ‘responsibilisation’ in healthcare highlight the importance of understanding the scope of responsibility ascriptions in this context. Research into the social determinants of health and psychological mechanisms of health behaviour (...) could undermine some commonly held and tacit assumptions about the moral responsibility of agents for the sorts of lifestyles they adopt. I use Philip Petit's conception of freedom as ‘fitness to be held responsible’ to consider the significance of some of this evidence for assessing the moral responsibility of agents. I propose that, in some cases, factors outside the agent's control may influence behaviour in such a way as to undermine her freedom along the three dimensions described by Pettit: freedom of action; a sense of identification with one's actions; and whether one's social position renders one vulnerable to pressure from more powerful others. (shrink)