This article reports empirical evidence about the influence of a pre-service methods course on preparing aspiring and practicing content teachers to work with adolescent bilingual learners in secondary schools. Qualitative methods were used to analyze the extent to which participants developed abilities to plan instruction and to think complexly about instruction for bilingual learners in mainstream classes. Data sources included surveys, observations, interviews, and student work including an electronic blog. Findings suggest that although participants felt more prepared to teach bilingual learners, their skill in planning instruction for bilingual learners and ability to think complexly about such instruction varied. Secondary content teachers also recognized roles as language teachers and advocates for immigrant and bilingual adolescents. Further research is recommended to follow participants into the classroom, provide site-based coaching, observe continued teacher development, and assess pupil learning.