Terry Moe's expansive yet incisive article extolling what he calls the “revolution” in presidential studies explicitly ties the progress of the presidency subfield to theoretical developments that have been critical to the mainstream of political science. This commentary shares Moe's positive view of these developments but departs from his negative view of other streams of work, especially Neustadt's contributions and the scientific empirical studies that he indirectly helped generate. Most particularly, Moe is attracted to theories of invariant behavior—that is, how any person should or would have behaved in the face of similar conditions. In studying the presidency, this is a necessary place to begin, but not always a sufficient place to end. Presidents remain important to the presidency because of their decision-making role amid uncertainty and ambiguity—precisely where people make a difference. Although we have virtually no usable theory of individual difference, which is usually unexplained residual variance, we can make use of observations to assess the way presidents do make decisions.