Instructional policy reforms that focus on standards and assessments have gained popularity in the last two decades. State governments, which had previously left most instructional matters to local governance, set challenging learning standards and developed related assessments and curricular frameworks. Despite their popularity and persistence, standards-based reforms face the challenge of successful local implementation. Occupying an intermediary position between the statehouse and the schoolhouse, the local school district has significant potential to influence standards implementation. It is important to consider the consequences for classroom instruction of what districts do in response to standards. While states may set standards and provide incentives for implementing them, district policies often determine how teachers comprehend the standards. This issue of CPRE Policy Briefs summarizes the findings of a recent book, Standards Deviation: How Schools Misunderstand Education Policy (Spillane, 2004), that examines state and local government relations as the standards move from the statehouse to the district policymakers and teachers who attempt to make sense of them. It takes a case study approach, focusing on a single state, Michigan, and strategically sampled school districts. The study is based on empirical data from a four-year examination of approaches to the use of standards in nine Michigan districts between 1992 and 1996. The sample included three midsize city districts, two suburban districts, and four rural districts. Mixed methods, including semistructured interviews, questionnaires, and observations, were used to gather data at state, district, and school levels on implementation of math and science standards. This overview of the study's findings first frames the subject of standards-based reform, and then moves to a discussion of the Michigan math and science standards. Variation in the progress of standards among districts is explored next, followed by a cognitive explanation for the variation and a discussion of districts' resources. Next, variation in teachers' beliefs about and implementation of the standards is analyzed. The overview closes with implications of the study for policy outcomes, analysis, and design.