This study unpacks the inherent tension that arises when any school adopts a particular model for reform--how to mesh a model with the reality of daily life in the classroom. In the field of bilingual education, programme models abound, and the literature reflects a great diversity among them, as well as efforts to evaluate their relative effectiveness. This interpretive, ethnographic study reveals how one particular programme model, two-way immersion, is enacted in the context of Monte Vista Elementary. The study illustrates the tension between the two-way immersion model and implementation at the school site. The staff developed a series of school-wide agreements regarding student placement, outcome goals, and literacy instruction. These agreements shaped the nature of literacy instruction, and for one teacher led to a focus on language of instruction rather than rich, authentic literacy events for all students.