In this article, we argue that institutional changes to the seniority system have electoral consequences to incumbents. Building on the theory of Conditional Party Government, we argue that the consolidation of power in the hands of party leadership reduces the electoral value of seniority. This reduction occurs because power that was previously in the hands of committee chairs, whose roles are obtained through seniority, is ceded to party leaders. By increasing the party’s brand, this centralization also delivers a dividend received by all members regardless of seniority. We present empirical evidence supporting this argument. Our findings suggest that the “condition” of Conditional Party Government, i.e., preference homogeneity among the majority party, is only a necessary condition; in order for centralization to occur, party reformers must also overcome the opposition of entrenched senior members.