In recent decades, the number of school-aged linguistic-minority students in the United States has increased dramatically. Society at large and public schools in particular must be prepared to respond to these students' needs. In public education, the bulk of this responsibility falls on teachers, who are called upon to apply educational policies and pedagogical practices in effective and humane ways. However, the majority of White, middle-class, monolingual English-speaking teachers will have little in common with these newcomer students in terms of background, culture, or language. Moreover, they also likely will have received little or no preparation to address the specific needs of these children who are significantly changing the demographics of U.S. public schools. In the preparation and training of language teachers, much of the attention is focused on imparting technical knowledge such as the various methodologies that will help them develop expertise in a range of subject areas. However, the reality is that language teachers will most likely work with non-White immigrants with low socioeconomic status (SES) and other linguistic-minority students from low-status cultural groups. Therefore, it is critical that the training of these teachers include an understanding that there are political and ideological dimensions to language education, particularly for vulnerable student populations, and that these factors can have an adverse impact on teachers' work with these students. In this chapter, the author describes the current effort of one graduate department of applied linguistics to develop a curriculum that prepares English as a second language (ESL)/sheltered English (SE) teachers more effectively by infusing one key critical pedagogical principle into the course of study: the role ideology plays in teacher preparation. The author first briefly discusses the field of critical pedagogy and the significance of studying ideology in any teacher preparation program. She then addresses what the literature reports about teachers' ideological orientations in terms of cultural, linguistic, and social-class diversity.