Many morally significant outcomes can be brought about only if several individuals contribute to them. However, individual contributions to collective outcomes often fail to have morally significant effects on their own. Some have concluded from this that it is permissible to do nothing. What I call ‘the problem of insignificant hands’ is the challenge of determining whether and when people are obligated to contribute. For this to be the case, I argue, the prospect of helping to bring about the outcome (...) has to be good enough. Furthermore, the individual must be in a position to increase the probability of its being brought about to an appropriate extent. Finally, I argue that when too few are willing to contribute, people may have a duty to increase their number. Thus, someone can be obligated to contribute or to get others to contribute. This prospect account is consistent with Kantianism, contractualism and rule consequentialism but inconsistent with act consequentialism. (shrink)