What philosophical motivations lay behind the emergence of the genealogical method in Foucault's thought? Pace traditional interpretations, I argue that genealogy is best construed as a supplementary addition to the archaeological mode of investigation. It addresses an issue that arose within the problematic to which the archaeological method responds, but which that method was not designed to solve: the problem of "transcendental genesis" as this issue was defined within the unique parameters set forth by the French phenomenological tradition.