This dissertation study explores how teachers perceive and use data to inform their instructional practices and ultimately impact student achievement. The research focuses on whether or not data availability impacted how often teachers used data for instructional purposes and if leadership and coaching practices impacted teachers' perception of the value of data analysis to make instructional decisions. Research showed that using various coaching practices and a distributed leadership style may positively impact how teachers perceive and use data. Administrative support and a knowledgeable data coach also may determine how likely teachers are to analyze and use available data sources. Having increased access to multiple data sources may increase the frequency of collaboration among staff members to make changes in instructional practices. This study shows that having more access to and conversations about data beyond state assessments leads to increased data use among staff members. However, the results also showed without a change in leadership and coaching practices, limited improvement in teachers' perceptions of the importance of data for instruction results. Maintaining a top-down approach to PLCs and collaborative team meetings and not providing enough training on adjusting instructional practices based on data analysis led to department members maintaining their perceptions that data is not necessarily an essential part of instructional decisions. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]