The Senate often disposes of substantial policy matters on the basis of a simple majority. The five policy studies--arms sales, the Panama Canal Treaties, strategic arms limitations, relations with Turkey, and nonproliferation--cover a wide range of problems. Characteristics that play an increasingly important role in making foreign policy in an interdependent world--economic interests, transnational actors, concerns about human rights--played subordinate roles in these policy studies. The Strategic Arms Limitation Talks (SALT) and Panama experiences show the Senate exercising its responsibility to advise and consent to treaties. The Panama treaties were approved by a narrow margin and only after a long and involved process; SALT II was never called up for debate on the Senate floor. Congress serves as a transmission belt between public opinion and national policy: it both reflects public preferences and contributes to shaping them.