It is widely assumed that Sumner coined the concept of ethnocentrism in 1906. This attribution is prominent in psychology and the social sciences and is found in major works on ethnocentrism, intergroup relations, and prejudice. A review of classic sources written in German, Polish, and English shows that the concept had existed in numerous publications for at least several decades before Sumner's writings on ethnocentrism (e.g., Gumplowicz, 1879, 1881). This article presents early conceptualizations of ethnocentrism and potential influences on Sumner. It also discusses implications of this conceptual history, such as biases that may have contributed to the widespread belief that Sumner coined the concept. It is argued that psychologists and other social scientists should stop attributing the origin of the concept to Sumner, despite his important role in popularizing it, and, in general, should engage more with their intellectual history in different languages.