What do constituents hold their representatives accountable for? Previous work outlines two distinct but often conflated theories of accountability: democratic theory suggests that voters respond to the policy positions representatives take; retrospective voting theories suggest that they respond to the outcomes of these policies. Using new survey data, this article demonstrates that perceived congruence with their senators’ policy positions influences voters’ decisions much more than do perceptions of peace and prosperity. This finding holds when correcting for endogeneity using instrumental variables analysis, when considering members of the majority and minority parties separately, and when looking at specific policy areas. Replicating previous studies of retrospective voting suggests that they overstated the importance of policy outcomes for congressional elections due to omitted variable bias. The buck that stops with Members of Congress is for the positions they take, not for the policy outcomes they preside over.