Based on an approximate eight month critical ethnographic action research project at a U.S. Midwestern high school in 2004-2005, this article presents data related to the linguistic ideology and associated cultural assimilationist attitudes and practices at Junction High School. During an intercultural peace curricula development project, members of a teacher inquiry group identified lack of empathy about non-English language use at school as "nonpeaceful" and in need of change. This article links linguistic normative monitoring practices with cultural assimilationist orientations enacted by several members of the local dominant Euro-American population. How social inequality and unequal power relationships are reproduced via restrictive practices on how students speak and on what languages they use when speaking in schools are important questions considered. Discussion focuses on the intersection of language, cultural power, and national identity. Broader ties to conservative ideological movements in the United States that focus on linguistic and cultural assimilation are explored.