The purpose of this study was to explore how teachers engaged in data use for instructional decision making. A grounded theory research design was used to analyze interviews of 10 special education teachers. Special education teachers were asked to complete an online survey and were interviewed with questions to reveal their experiences with student data, and what potential barriers and facilitators they face during the data use process. The survey was used to provide informative data on teachers' dispositions toward data use. The theory generated from the data, Theory of Teachers' Data Use Engagement, proposes that teachers' understanding of data, collaboration with others, professional development, resources available, and district wide implementation and tools affect their data use experience. The coding process, the themes generated from codes, and the final theory are presented. The discussion provides a comparison between results from this study and previous literature, limitations of the study, and recommendations for future research. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]