As writing has assumed increasing importance in discussions of pedagogy for diverse classrooms, attention to the contexts in which secondary teachers develop and implement writing instruction for adolescent English language learners (ELLs) is of great importance. Drawing on ecological language learning theories and situated teacher learning theory (van Lier, 2003; Borko, 2004), the authors present findings from participants in a focus group (N = 10) and follow-up interviews (N = 6) conducted with a set of secondary English language arts and English as a second language (ESL) teachers. Within overlapping institutional/professional and pedagogical contexts, teachers identified teacher expertise, high-stakes testing, classroom assessment and grading, placement and tracking, and disciplinary disconnects as the ecological factors most influential in their instructional choices related to ELL writers. Implications of these findings for research and teacher education are discussed.