In 1926 Weimar photographer László Moholy-Nagy predicted that the illiteracy of the future would be ignorance not of reading or writing, but of photography. Five years later theorist Walter Benjamin described the ability to compare facial types via portrait photobooks as a vitally important skill. As Germany endured an interregnum identity crisis, the photographic book proved an effective alternative to what were perceived to be the more subjective, traditional “fine arts” of painting and sculpture. More than innocuous collections of fine art photography, these books functioned as physiognomic guidelines for the representation of national identity during Germany's turbulent transition from unstable democracy to totalitarian state. As conservative writer Ernst Jünger observed in 1934, portrait photobooks offered “a particularly effective means of tracking down the enemy's individual character,” because it is “easier to change one's views than one's face.” This essay charts portrait photography's exploitation as evidentiary support for nineteenth-century physiognomic theory and examines a resurgent interest in this outmoded “pseudoscience” in 1920s Germany. My analysis of the production and reception of two popular photobooks, one by Weimar photographer August Sander (The Face of Our Time), and the other by Nazi photographer Erna Lendvai-Dircksen (German Folk Faces), reveals the degree to which both progressive and reactionary factions relied on photography and physiognomy to help redefine a stable or “authentic” face of the nation in an otherwise unstable time. While Hitler's devotion to both photographic propaganda and biological determinism is well known, the fact that progressive Weimar photographers like Sander also believed in the medium's power to lay bare the nation's “true” character and corporeal countenance indicates a surprising cultural continuity between the two regimes downplayed by art history's focus on the Führer's repudiation of modern art. By exploring the way that two ideologically opposed photographers shared a reliance on physiognomic theory, this research demonstrates portrait photography's central importance within the discourse of modern German visual culture and challenges art history's persistent emphasis on aesthetic rupture, rather than cultural continuity, between Weimar and the Third Reich.