Research has shown that exposure to the national flag alters people's behavior and political and intergroup judgments. In several field studies conducted in an area of France with a strong regional identity, we examined the effect of the presence of the regional flag versus the national flag versus no flag on behaviors. Various situations (e.g., money solicitation, implicit helping behavior, food tasting) were tested in Brittany, on the French west Atlantic coast. Car drivers, passersby in the street, and patrons in bakeries were exposed to no flag versus the French flag versus the Brittany flag held by requesters or presented on a product or on a car. Findings showed that the regional flag increased helping behavior dramatically. Other studies also revealed that the presence of the Brittany flag reduced aggressiveness and influenced preference for food products. The power of a flag as a symbol that could increase in‐group membership is discussed.