This paper surveys the current philosophical discussion of the ethics of risk imposition, placing it in the context of relevant work in psychology, economics and social theory. The central philosophical problem starts from the observation that it is not practically possible to assign people individual rights not to be exposed to risk, as virtually all activity imposes some risk on others. This is the ‘problem of paralysis’. However, the obvious alternative theory that exposure to risk is justified when its total benefits exceed its total costs faces the standard distributional challenges of consequentialism. Forms of contractualism have been proposed as a solution, but how exactly such theories can be formulated remains problematic, especially when confronted with the difficult cases of mass, novel, risk such as climate change.