Schools are realizing that carefully collected and analyzed data represent the key to educational improvement. This digest outlines the most useful types of data to drive the school-improvement process, steps that must be taken to collect and analyze data, the role of administrators in guiding the data-driven reform process, and results that can be expected. Data provide an accurate way to identify problem areas in school programs, reveal strengths and weaknesses in students' knowledge and skills, and provide meaningful guidance on how teaching practices can and should be altered. The most useful types of data include student assessment data, student demographic data, perceptions data, and school program data. Through data-driven inquiry, school staff can identify areas in need of improvement, select high-priority problems for correction, and outline improvement strategies. After plans of action have been implemented and completed, school staff can continue data collection and analysis to determine whether to modify or discontinue corrective actions. Principals and other administrators can best support data-driven reform processes by providing vision and leadership. Results can include a higher level of student achievement and the school assuming a more professional and civil culture of inquiry. (Contains 11 references.) (RT)