This study explores teachers' first enactments of a set of theory-based curriculum materials designed to support academic language instruction. Specifically, this multiple case study looks at how six middle school English teachers in three US schools adapted the materials; each case includes a pair of teachers, one novice and one more experienced. All schools were located in the same district where a school performance measurement system was being used to publicly rank schools' academic performance and growth. Multiple measures were used to look for evidence of adaptations and why teachers made adaptations. We found that all teachers adapted the curriculum, most often in response to either perceived student needs or district reform pressures. In two cases, patterns of adaptation differed by teacher experience; experienced teachers appeared better able to adapt curriculum materials to meet instructional goals. This pattern did not hold up at the third school, where teachers faced greater reform pressures. Taken together, these findings suggest that researchers should pay more attention to the role of school and district policy on teachers' enactments of theory-based reforms. We conclude with guidance to researchers, instructional leaders and others interested in the potential of theory-based curricula as a lever for improving classroom instruction.