Congressional scholars have vastly underappreciated how representation in the U. S. Senate differs from the House of Representatives. In this provocative new study, Wendy J. Schiller develops a theory of dual representation--where two legislators share the same geographical constituency--to explain Senators' behavior. Noting that Senators from the same state join different committees, focus on different policy areas, and address different economic interests through bill and amendment sponsorship, the author examines the electoral and institutional forces that elicit this competitive behavior. In developing her theory, Schiller relies on a wide variety of methodologies, from statistical analysis to case studies, and makes telling comparisons with similar situations in Latin America and Asia. Partners and Rivals argues against the commonly held view that individual Senators do an inadequate job in representing their states. Instead, this book demonstrates how the competitive structure of Senate delegations creates the potential for broad and responsive representation in the Senate. When two senators from the same state are viewed as a pair, it becomes clear that their combined representational agendas include a wide range of the interests and opinions that exist among constituents in their state. This holds true whether the Senators are from the same party or not. Rich in details, Partners and Rivals is the most thorough and rigorous explanation of Senators' behavior available.