Together we can often achieve things that are impossible to do on our own. We can prevent something bad from happening, or we can produce something good, even if none of us could do it by ourselves. But when are we morally required to do something of moral importance together with others? This book develops an original theory of collective moral obligations. These are obligations that individual moral agents hold jointly but not as unified collective agents. The theory does not stipulate a new type of moral obligation but rather suggests that to think of some of our obligations as joint or collective is the best way of making sense of our intuitions regarding collective moral action problems. Where we have reason to believe that our efforts are most efficient as part of a collective endeavor, we may incur collective obligations together with others who are similarly placed as long as we are able to establish compossible individual contributory strategies towards that goal. The book concludes with a discussion of 'massively shared obligations' to major-scale moral problems such as global poverty. Getting Out Act Together: A Theory of Collective Moral Obligations will appeal to researchers and advanced students working in moral, political and social philosophy, philosophy of action, social epistemology and philosophy of social science.