With the passage of the No Child Left Behind (NCLB) Act of 2002, schools, districts, and therefore, superintendents have been held increasingly accountable for the achievement of the students. The states and federal governments have used student achievement data to measure the progress and success of schools and districts and have held districts accountable to this data. This study examined the use of data by superintendents in their decision making related to student achievement. The study looked at what competencies they possessed in the use of data and how they learned those competencies, and what types of data they used and valued. The study also identified what actions, policies, and communications superintendents used to promote data use among all of the educators in their districts. Superintendents' use of data in the evaluation of principal, teachers, and educational programs was also included in this study. This study used a mixed-methods (quantitative and qualitative) approach to examine a population of 23 superintendents from urban school districts in California. All of the participating superintendents had been in their position for at least two years and demonstrated improved student achievement as measured by their API scores. All 23 superintendents responded to a 45 questions Data-Driven Decision Making Survey Questionnaire designed to measure and identify specific skills they possessed, the level of those skills, and for what types of decisions did they use those skills. It identified which types of data they believed valuable and which they used in a set of decisions that superintendent often make. It also measured the frequency that they engaged in certain data-driven decision making actions. Five superintendents whose responses and reputations indicated that they effectively used data in their decision making were selected from the group of 23 and participated in personal interviews. They responded to 13 pre-selected questions designed to elicit detailed information in the same areas as the surveys. The research study made several significant findings. Participating superintendents reported that they possess nearly all of the competencies needed to make effective-data driven decisions and that they learned most of these competencies through on-the-job experiences rather than any type of formal training. These superintendents identified CST data, benchmark data, and program data as the types that they used and valued in making most of their decisions. The results indicated that the actions superintendents were most effective in for the purpose of promoting data use among all educators in their districts were: communicating district goals, expectations, and results using data, and providing the time and resources for using data to teachers. The study revealed that the superintendents used data effectively in evaluating their principals and programs, but did not use data in the evaluation of their teachers. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]