This chapter outlines the processes that were at work to make the leaders so powerful vis-a-vis committee chairs and rank-and-file members. It describes the goals of congressional parties. The chapter shows the conditions that fostered the growth of the party leaders' powers. It also outlines these powers. Party leadership was either the repository of the power relinquished by committees as a result of the reforms or it was the cause of the reforms themselves. The development of party platforms, their contestation during elections and their implementation are the means by which voters cast their ballots in congressional elections. Political scientists have utilized two features of Congress to make the task more manageable. First, the Constitution dictates and the chambers have developed rules, structures, and institutions that prescribe a more systematic pattern. Second, Richard Fenno and David Mayhew have provided analytic leverage for predicting legislative outcomes by outlining the goals of individual members.