We examine two competing arguments relating to the role of Congress in explaining presidential decisions to use force from 1953 to 2000. We offer a policy availability rationale that suggests Congress matters in the decision to use force because presidents are motivated by their ability to influence legislative policy making. The models demonstrate that presidential success in Congress is the significant factor determining military action, not party control. Presidents employ force when their ability to influence policy is weak and avoid military actions when Congress supports the president's agenda. The results speak to the intersection of two important literatures, namely, presidential unilateralism and conventional theories on domestic politics and the use of force.