Moral duties are regularly attributed to groups. We might think that the United Kingdom has a moral duty to defend human rights, that environmentalists have a moral duty to push for global systemic reform, or that the affluent have a moral duty to alleviate poverty. This book asks (i) whether such groups are apt to bear duties and (ii) what this implies for their members. It defends a ‘Tripartite Model’ of group duties, which divides groups into three fundamental categories. First, combinations are collections of agents that do not have any goals or decision-making procedures in common. Combinations cannot bear moral duties. Instead, we should re-cast their purported duties as a series of duties—one held by each agent in the combination. Ea...