I examine the differential responsiveness of U.S. senators to the preferences of wealthy, middle-class, and poor constituents. My analysis includes broad summary measures of senators’ voting behavior as well as specific votes on the minimum wage, civil rights, government spending, and abortion. In almost every instance, senators appear to be considerably more responsive to the opinions of affluent constituents than to the opinions of middle-class constituents, while the opinions of constituents in the bottom third of the income distribution have no apparent statistical effect on their senators’ roll call votes. Disparities in representation are especially pronounced for GOP senators, who were more than twice as responsive as DEM senators to the ideological views of affluent constituents. These income-based disparities in representation appear to be unrelated to disparities in turnout and political knowledge and only weakly related to disparities in the extent of constituents’ contact.