In the eyes of many German and French doctors, the First World War represented an immense field of observation that had to be evaluated practically and scientifically. The opportunity to place such a large number of people under medical care and to have an educational effect on their health behavior was unique. In a kind of oversized experimental set-up, doctors diagnosed the constitution and state of health of the war society and made a prognosis about the future chances of recovery of the battered "national body". Susanne Michl compares German and French doctors and asks whether, when faced with the same social problems, they came to comparable social diagnoses and recommendations for action.