Concentrating on the health sector, this article argues that the provision of collective goods through external actors depends on the level of state capacity and the complexity of the service that external actors intend to provide. It shows that external actors can contribute most effectively to collective good provision when the service is simple, and that simple services can even be provided under conditions of failed statehood. Effectively delivering complex services requires greater levels of state capacity. The article also indicates that legitimacy is a key factor to explain variance in health service delivery. To demonstrate this, the article assesses health projects in Somalia. It shows that simple services—malaria prevention and tuberculosis control—are provided effectively in all three Somali regions, including the war-torn South-Central region. In contrast, the HIV/AIDS project only achieved substantial results in Somaliland, the only region with a comparatively higher level of state capacity, and failed in the South-Central region and Puntland.