The effect of foreign policy on terrorism is an important area of research that bridges work on international relations and intrastate conflict by highlighting how an outside country can influence attacks from a nonstate actor in another country. Research in this area is important for understanding how countries like the United States can best deal with the threat of international terrorism. Research has generally demonstrated that states with active foreign policies are more likely to experience international terrorism, particularly democracies and the United States. This has been hypothesized to occur because active foreign policies create blowback, or negative feelings toward a state, leading to greater acts of terrorism against that state. Beyond the effects of a state’s general foreign policy, others have looked at more specific policies, such as military occupation and intervention. This body of research argues that international terrorism is often a response to perceived occupation of an area. Groups see terrorism as a method to dislodge the occupying force. This argument has been refined by other scholars, who have presented conditions or extensions of this argument. Others have focused on military intervention, arguing that the presence of troops, the negative sentiment that they evoke, and their effect on strengthening the government all create incentives for groups to attack the foreign power that has deployed troops. Foreign aid has been seen as a policy that can address the threat of terrorism. Aid has been argued to be able to improve local conditions and incentivize and reward local states for engaging in counterterrorism. Others have presented conditions under which aid is more or less likely to be effective, including the idea that military aid might actually increase the amount of terrorism, for reasons similar to military intervention, and create an incentive for states to maintain a terrorist threat. Other foreign policy approaches have focused on legal attempts to stop terrorists from financing their organizations. These policies have been driven by the United Nations, coalitions of states, and individual states. This article also focuses on the methodological issues that all these studies face, as well as future research directions.