In this examination of Mexican-American bilingual college writers, it is argued that implicit language ideologies, common misconceptions about bidialectalism/bilingualism, and the classroom attitudinal domain subvert the success of ethnolinguistic minority students. The author designed and conducted a randomized language attitude survey (N = 195) of 1st-year composition students on the assumption that language attitudes, reflective of the social/ethnic/linguistic polarization of south Texas, exist inside the English classroom. Findings correlate the multiple ethnolinguistic identities of this student population with language myth adherence. Results reveal the tendency among college writers for subscription to various language myths: dialect misconception, English bias, language purity myth, literacy myth, misconception of oral performance.