Public administration scholars and practitioners uniformly agree that saddling agencies with multiple mandates breeds dysfunction and impedes performance. However, less is known about the mechanisms by which combining purposes has these effects. This study of a broad set of U.S. federal agencies finds support for the conventional wisdom by showing that agencies balancing greater numbers of programs perform worse. The analysis further suggests that such organizations struggle largely because they are more likely to be forced to simultaneously adopt conflicting stances toward program targets. Moreover, when programs force agencies into conflicts in which they are asked to both support and restrain the same target, the resulting uncertainty among personnel regarding agency priorities helps explain why operations are negatively impacted. Thus, it is not simply that accumulating missions impedes agency performance but rather how those competing mandates interact that can define whether an agency will struggle to achieve its objectives.