Because the constitutional separation of powers often leads to delay or obstruction rather than coordinated policymaking, U.S. presidents are increasingly acting unilaterally to move policy. With the issuance of executive orders, signing statements, and policy memoranda, unilateralism has become a defining feature of the American presidency. Can Congress effectively use checks and balances to counter presidential unilateralism? Strategic Responsiveness takes a theoretically developed and empirically oriented approach— situated within legal and historical contexts—to explore the system of separated powers. The authors find that Congress is not as weak as many perceive it to be and show how members of Congress often anticipate individualized policy loss and choose to respond. These policy struggles shape the constitutional order as surely as broad, statutory constraints might. While the aggrandizement of the presidency and the usurpation of congressional control are not countered, ordinary policy losses are. For members and senators, presidential overreach is fine as long as the policy wins continue, but policy losses may motivate members to reassert congressional prerogatives in policymaking through increased oversight. Strategic Responsiveness reveals how profoundly important policy-level disputes are in the politics of maintaining a particular constitutional order.