The rivalry between France and Germany predates the formation of their modern nation-states and has attracted attention since the first century BC when Cesar wrote of the competition and cultural differences between the Galli and Germani. The confrontation between these two national groups is normally identified as the genesis of violent military conflict and recurring crises, yet it also gave rise to an extremely fruitful competition in the decorative arts and architecture during the early twentieth century, culminating in the 1930 Parisian salon of the Société des artistes décorateurs. This dissertation argues that the national and commercial rivalry between France and Germany was a key driving force in the development of modernism in the first three decades of the twentieth century, stimulating the creation of a variety of new artistic forms. By examining several pivotal exhibitions and exploring the connections between the domestic sphere, consumerism, and nation-state building, this study offers a new perspective on the evolution and maturation of Art Nouveau, Art Deco, and the International Style. Additionally, it investigates how these movements were received and adapted in America, which emerged as a significant site of French-German artistic exchange after their rivalry crossed the Atlantic.