One of the challenges confronting teachers today is effectively using data to drive instructional decisions-making in their classrooms. The purpose of this study was to examine whether professional development and the use of coaches in the area of data-driven instruction impacts classroom instructional practices and how student achievement could be influenced by the shift in instructional and assessment practices. The researcher collected three years of ex-post facto observational data and student assessment results from a cohort of eleven middle school teachers and 1,372 middle students from 2006 through 2008. The researcher examined the data to see if the professional support the teachers received in instructional decision-making had changed or influenced teaching pedagogy and had an impact on student assessment results. The results of this study indicate that the relationship between the professional development and support given to the teachers has an impact on teachers use of data-driven decision-making and the implementation of best practices by classroom teachers. The change in classroom pedagogy had an impact on student achievement. The establishment of support had influenced the teachers' use of data, changed instructional decision-making practices, and increased student achievement of state assessments. [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.]