Recent research surrounding educational leadership indicates that among school-related factors, leadership is second only to the classroom teacher as a variable associated with improving student achievement (Leithwood et al., 2004). Given the current climate of high stakes testing and accountability, the role that the principal plays in fostering continuous school improvement and ensuring academic success for all students has become increasingly important. To enhance school performance, the literature proposes that school leaders serve as instructional leaders and distribute their leadership responsibilities. One significant element of such leadership models is the ability of the school principal to support and promote inquiry by teachers and school administrators into student and school data. Wayman and Stringfield (2006) note that a campus culture that values and practices data-based decision making is marked by collaborative inquiry into student data. Advocates of data-driven decision making and data use suggest that inquiry into student data has been shown to be useful in improving overall school practice (Bernhardt, 2003; Wayman and Stringfield, 2006). Furthermore, using data to focus on specific goals will improve student learning (Schmoker, 1999). To explore how principals can foster the development of structures that allow for inquiry into student and school data, a case study of one purposely-selected high school was conducted. The four primary research questions this study addressed were: (1). What structures can high school principals develop and implement that promote inquiry by teachers and administrators into data? (2). What structures positively impact student academic achievement, as perceived by high school teachers and principals? (3). How are teachers using student achievement data in their instructional decision-making? (4). What are the qualitative data elements that school leaders might consider to inform the ongoing planning and decision-making process? Over the course of four months, data was gathered through individual interviews, observations, a survey, and analysis of pertinent documents. Several themes surrounding data analysis and leadership practices emerged. These included: the benefits of using structures to empower school staff to own data, the use of structures to allow for time for collaboration, using data to improve teaching practices, and the benefits of providing teachers greater access to pertinent data. / text