Approaches to teaching critical language awareness are gaining traction in urban schools with culturally and linguistically complex student populations; however, what teachers need to know to enact these pedagogies is not well understood. Using a lens of pedagogical content knowledge for critical language teaching, this study examines what happens when a teacher implements a critical language pedagogy without attention to student understandings of language variation. The findings suggest that when student knowledge is not valued, students may be resistant to linguistic terms and concepts, despite teachers' linguistic content knowledge and pedagogical approach.