This article investigates how the U.S. government prohibited the use of the Japanese "enemy" language at Japanese American "assembly centers" during World War II. Using archival government documents, this study demonstrates that assembly camp authorities curtailed Japanese American evacuees' First Amendment rights. By issuing various regulations and orders, camp officials outlawed the publishing, writing, and reading of Japanese literature of all kinds. They also banned Japanese-language assemblage, worshipping, cultural events, and recreation. Thus, evacuees at assembly camps, especially the older generation who lacked education in the English language, were deprived of their most essential means of self-expression.