Ex ante contractualism holds that in situations involving risk we ought to act in accordance with principles that license the action that satisfies the strongest individual claim, where those claims are a function of the expected value that a given policy gives each person ex ante. I here challenge ex ante contractualism on contractualist grounds. I argue that adopting ex ante contractualism would have far reaching implications that contractualists, or many nonconsequentialist in general, would find very hard to accept. I conclude that to block these implications, contractualists should adopt an ex post approach to deal with decisions under risk.