Intended to help secondary and college students and adults develop a clearer understanding of how our democracy works, this booklet examines how Congress makes legislative decisions and how it collects the information necessary to legislate. With 100 Senators, 435 Representatives, and 20,000 staff people receiving and processing information, decision-making in Congress is a very complicated process. As they make legislative decisions, members of Congress use many information sources, including personal staff recommendations, constituent letters, other members of Congress, the media, lobbyists, and committee staff research. Members rely a great deal on their staffs to brief them on the details of proposals. Legislative staff must also answer constituent mail. Staffers use a variety of services, publications, and information sources, e.g., committee hearings, House Information Systems, the Congressional Research Service, the Congressional Record, and caucuses. A survey of 123 congressional staff members has shown that spontaneous individually composed letters are the most effective way of communicating with congressional decision-makers. (RM)