We offer a theory of the direction and nature of representational linkages between constituents and their elected representatives based on two attributes of issues: their complexity and their relationship to the lines of partisan cleavage. We show that the theory is compatible with the existing evidence on representation and then offer results of tests of new predictions from the theory for both simple and complex party-defining issues. For additional evidence of the dyadic basis of these findings, we also show that the strength of the observed linkages varies in accordance with theoretical expectations about the seniority of members of Congress and, for senators, recency of election. We also explain how the theory can account for a number of seemingly contradictory empirical findings in the large literature on policy representation and how it allows scholars to make precise predictions about the characteristics of representational linkages.