The use of assessment data to inform instruction is an important component of a comprehensive standards-based assessment programme. Examining teachers' data use for instruction can reveal the extent to which instruction is aligned with established content standards and assessment. This paper describes results of a qualitative study of teachers' data use in a mid-Atlantic metropolitan area in the United States. Focus group interviews with 60 upper elementary and middle school teachers from 45 schools were conducted. Findings indicate teachers aligned instruction and assessments with the state curriculum with the goal of improving student performance. While teachers found day-to-day informal assessments essential to shaping instruction, periodic formal assessments helped them monitor student progress and remediation efforts. Teachers described challenges associated with the misalignment of periodic assessments with instructional content, the breadth of content and higher cognitive demand expected in the newer state curriculum and the lack of infrastructure to support data use. [This article was published in "Perspectives in Education" (EJ1130896).]