Test-based accountability programs are designed to promote improved standards of teaching and learning within the systems of education that they are connected to. Brenan [Brenan, A. L. (2006). "Perspectives on the evolution and future of educational measurement." In: Robert (Ed.), "Educational measurement" (4th ed., pp. 1-16). Westport, CT: Praeger Publishers], however, suggests that little evidence exists to support the claim that these standardized assessment programs are achieving this goal. This study examines a Canadian high-stakes writing assessment's effect on the teaching of writing in three grade 12 academic English classrooms. Analysis across cases revealed that factors shaping the exam's impact on teachers' pedagogical choices include their attitude toward the exam, the pressure they felt from their school communities and their years of experience. The study also found that the exam caused teachers to narrow their teaching of writing in relation to processes taught, assignment design, and evaluation criteria utilized. The study concludes that in the cases observed, the exam is having a negative impact on the teaching of writing. (Contains 1 table.)