Teachers' understandings of second language learning influence their practices in the classroom. This paper analyzes interview and classroom data collected during a year-long ethnographic study of two high school English language development classes to identify (1) what the teachers understood about second language (L2) development and L2 academic writing, and (2) to what extent these perspectives manifested in the teachers' writing instruction. Analyses suggest that both the teachers felt that language could be learned inductively through exposure to models and that writing instruction should focus on essay structure and correctness. Their teaching, however, was also constrained by accountability pressures from high stakes writing assessments. I argue that the teachers' approaches reflected a restrictive understanding not aligned with a situated perspective on language and writing development and therefore denied their multilingual students' opportunities to learn academic language for writing.