Since the enactment of the No Child Left Behind Act (NCLB) in 2001, United States federal and state governments have been active in constructing initiatives and accountability measures in the hopes of improving student achievement. This has had a profound effect on the roles performed by elementary school principals in an effort to attain benchmarks. One of the new tasks is to assume the responsibility of data analysts. However, do these administrators have the data literacy/competency to carry out this work? The current body of empirical literature on this matter is limited. The primary focus has been on how data can help inform decisions regarding teacher instruction and thus positively affect student learning. This study interviewed 12 elementary school principals from Alabama, California, Washington, and two provinces in Canada – Alberta and Ontario. As well, documents used as sources of data to assist decision making were examined. Employing the design of grounded theory, the study gathered information about principals’ knowledge/skills regarding data, the role of data at their schools, and their descriptions of data. To accomplish the task, three research questions were developed: (1) What knowledge/skills are behind the use of data by elementary school principals? (2) How do elementary principals view the role of data in leading school improvement? And, (3) How do elementary principals describe their use of data in leading school improvement? The study’s findings disclosed comparable themes mentioned in empirical literature from the past 10 years indicating principals’ heavy reliance upon summative assessments to make decisions concerning teacher classroom instruction. Furthermore, the pressures of accountability measures in the form of benchmarks played a significant role when it came to planning school initiatives. Merging evidence from interviews and empirical literature the researcher proposes an incipient framework explaining the knowledge/skills, description, and role of data concerning elementary principals data literacy/competency. Within this framework the category “Diagnosis of Data” is introduced to further explicate the concept of data literacy.