In the current climate of accountability, action research is one way for teachers to evaluate instructional changes designed to improve assessment results. It may become increasingly common for administrators to mandate teacher involvement in action research, yet few studies have been conducted in such settings. This article focuses on one middle school where the principal mandated action research for all teachers. Projects were carried out within academic departments, and department chairs were given latitude in how to organize and implement projects. This study explores project implementation and teacher perceptions of the action research. Interviews were used as an appropriate tool to explore teacher perceptions, with document analysis providing triangulation. Results from interviews of administrators, department chairs, and department members suggest an overall positive attitude toward action research, as well as variation in how action research projects were carried out. Differences occurred across several dimensions of action research, including context, motivation/ purpose, definition of action research, and organization of projects. Variations appeared to be influenced by each department chair's experience with action research and approach to departmental work, and each department's history of working together on instructional improvement efforts. This study suggests that administrators who mandate teacher participation in action research projects need to think about both the positive (providing teacher ownership and interest within the mandated context) and problematic (possibly leading to variation in the instructional impact of projects) aspects of project variation.