["The Economic History Review, EarlyView. ", "\nAbstract\nWhen studying French prices between 1938 and 1949, economists and historians face a paradox: whilst a vast black market shaped daily life, official indices recorded only state‐controlled prices. This article addresses the issue by introducing a new consumer price index that incorporates both official and black market prices. Drawing on extensive new data, it quantifies black market activity and estimates household reliance on it. As a result, the price dynamics have been considerably under‐evaluated between 1940 and 1944, and equally considerably over‐evaluated between 1944 and 1948. The index reshapes our understanding of price dynamics by challenging the common narrative that the Vichy regime successfully tamed wartime inflation whilst the postwar democratic regime failed to control it. Instead, the apparent postwar acceleration of inflation is revealed as a statistical illusion. Consequently, we show that real wages dropped dramatically during the German Occupation of France, which proves much more consistent with contemporary testimonies.\n"]