This case study of one middle school focuses on improving teachers' skills in data-driven decision making through analysis of student work and their own professional practice. The expectation that schools will make adequate yearly progress has pushed evaluation practice down to the teacher level, where teachers are asked to analyze and disaggregate standardized test scores to facilitate instructional decision making that will lead to increased student achievement. The authors analyze this change in relation to No Child Left Behind and to the literature on evaluation capacity building within schools.