Ideologies regarding what is "good" teaching undergird common teaching practices and pedagogical decisions, which may support and/or run counter to the broader policy environment in which they occur (Gibson, 1998). Drawing from a six-month ethnography of 10th-grade newcomer students from Mexico and their teachers in a Central Texas English high school English-immersion program, this article explores seemingly contradictory teacher practices regarding the use of English and Spanish in the classroom. I argue that these varying practices represent a tension between the school's official English-only policy and a broader political ideology prioritizing performance on standardized tests that led to allowances of student Spanish language use. These findings add to our understanding of the influence and effects of standardized testing on teacher and administrator priorities and the potential cost to the real-world language needs of newcomer students.