<p>The Puzzle of Collective Duties concerns a tension between the moral requirements of non-agential groups and two important principles of ethical theory, namely Ought Implies Can and the Moral Agency Principle. According to the Moral Agency Principle, if A has a moral duty, then A must be a moral agent. Non-reductionists hold that these moral requirements are not fully reducible to and explainable in terms of individual duties. But non-agential groups are not moral agents, which means that attributing a collective duty to the group violates the Moral Agency Principle. To solve this puzzle, Bill Wringe has given several arguments for rejecting the Moral Agency Principle. In this paper, I defend the Moral Agency Principle against Wringe’s arguments. The Moral Agency Principle is a central principle of ethical theory, and rejecting it is extremely costly. First, I argue that the Moral Agency Principle follows from our best meta-normative theory about normative reasons, which helps to explain the importance and centrality of this principle. Next, I argue against Wringe’s arguments for rejecting the Moral Agency Principle. Most importantly, I argue that this leads to the Demarcation Problem: There is no longer a principled way to draw the borders of the moral community of duty-bearers, which threatens the coherence of our entire ethical theory. Finally, I argue that, <i>if</i> non-reductionism is correct, there are three more attractive alternatives to rejecting the Moral Agency Principle for solving the Puzzle of Collective Duties.</p>