My dissertation takes up the multiplicity of German classification systems for mental illness that developed under the aegis of urban university clinics during the second half of the 19th century. I suggest that these systems are the starting point for investigating the presence of diagnostic models, representations of psychiatric diagnosis and psychological disturbance in modernist literature in Germany and Russia between the 1880s and 1920s. By tracing patterns of diagnostic discourse in authors such as Rainer Maria Rilke, Arthur Schnitzler, Alfred Döblin and Gottfried Benn in Germany and Anton Chekhov, Nikolai Evreinov and Andrei Platonov in Russia, I argue for an overlooked resonance between evolving classificatory systems for mental illness and the parallel investigation of the forms, codes and structures shaping the pathology that repeatedly appears in these authors' works. By returning to psychodiagnostic models "lost" or "discarded" in the quest for standardization, my research asks: In what specific ways did the shifting terrain of psychological pathology provide a resource for literary exploration? How were different historical modes of conceptualizing psychological affliction manifested in a literary context and how did they change once there? What were the specific points of crossover between literary production and clinical evaluation and what more diffuse elements contributed to similarities between the two? Were there instances where literary diagnoses trickled back into clinical practice? A ten-month SSRC IDRF would allow me access to the rare print materials, unpublished case histories, manuscripts and correspondence available at archives across Germany and Russia.