Few issues are more important to scholars of security studies than understanding the impact of state sponsorship on the capabilities of non-state armed actors. The subject of our study—Lebanon's Hezbollah—was selected based on its reputation amongst scholars and policymakers alike as an exceptionally capable organization. In our inquiry, we seek to answer the following questions about Hezbollah's rapid emergence during the 1980s as one of the world's premier armed non-state actors: (a) how did Iranian sponsorship contribute to Hezbollah's effectiveness?; and (b) to what extent did Hezbollah's success depend on characteristics endogenous to the organization itself? To preview our conclusions, state sponsorship can contribute markedly to non-state actors' capabilities by providing resources and sanctuary. However, the ultimate effectiveness of non-state armed groups depends heavily on such internal characteristics as their decision-making processes and members' backgrounds. Thus, while state support may be necessary for non-state actors to achieve their goals, it is insufficient as a guarantee of their effectiveness.