This study investigated teachers' beliefs about the changes needed to improve student learning in low-performing schools. The study employed a new instrument, the Need for Change Assessment (NCA), which solicited teachers' perceptions of the need for change in areas such as reading and math programs, classroom instruction, and school policies. Teachers in 15 elementary, middle, and high schools in four states participated (N = 320). Factor analysis revealed two factors and showed that the NCA possesses sufficient internal consistency to justify its use by researchers and practitioners. In the aggregate, teachers were more likely to identify change as necessary in areas that did not involve their own practice. A school-level comparison of survey results revealed that high school teachers were more likely to see the need for change in their schools than were elementary and middle school teachers. Perceptions of the need for change varied substantially between schools; no two schools were alike. Finally, the authors found that teachers and principals may differ in their perceptions of what needs to change. This study has implications for how low-performing schools may undertake improvement efforts, specifically regarding which stakeholders drive change and how they do so. (Contains 4 tables.)