This article argues that to determine the nature of the relationship between presidential approval and congressional support, one needs to reason more carefully about the theoretical underpinnings of the relationship and employ more rigorous designs for tests that evaluate this theorizing. The article begins by considering the views of presidents, White House aides, and other Washington insiders. It then outlines the reasoning behind hypothesizing that presidential approval would influence votes in Congress. There are two basic approaches to investigating the impact of presidential approval on congressional support for the White House. The theoretical thinking is vital as a foundation for developing and testing hypotheses.