Abstract: Do advisers affect foreign policy and, if so, how? Recent scholarship on elite decision making prioritizes leaders and the institutions that surround them, rather than the dispositions of advisers themselves. We argue that despite the hierarchical nature of foreign policy decision making, advisers’ predispositions regarding the use of force shape state behavior through the counsel advisers provide in deliberations. To test our argument, we introduce an original data set of 2,685 foreign policy deliberations between US presidents and their advisers from 1947 to 1988. Applying a novel machine learning approach to estimate the hawkishness of 1,134 Cold War–era foreign policy decision makers, we show that adviser-level hawkishness affects both the counsel that advisers provide in deliberations and the decisions leaders make: conflictual policy choices grow more likely as hawks increasingly dominate the debate, even when accounting for leader dispositions. The theory and findings enrich our understanding of international conflict by demonstrating how advisers’ dispositions, which aggregate through the counsel advisers provide, systematically shape foreign policy behavior.