What has caused the secular (long-term) decline in presidential domestic policy-making activities over the past several decades? In a previously published article in this journal, Paul Light provides several interesting speculative reasons for this trend. I propose a general explanation for the secular decline in presidential domestic policy making that centers on the rising organizational size and scope of the institutional presidency. Specifically, I argue that the American presidency's greater than optimal organizational size and scope has hurt its domestic policy-making activities in absolute terms. The suboptimal organizational size and scope of the presidency has also led to a deterioration of its institutional comparative advantage in policy-making activities vis-à-vis Congress. Therefore, twenty-first century American presidents possess a strong incentive to restrict the organizational size and scope of the Executive Office of the President as a means to strive for optimal institutional performance.