The purpose of this applied research study was to strengthen Tier I instruction within seventh and eighth-grade mathematics classrooms. This applied research study uses three elements; professional learning communities, consistent content-specific professional development, and increased student achievement to strengthen Tier I instruction in middle school mathematics and measure student academic growth. Interviews, surveys, statewide assessments, and benchmark scores were used in this study as measures for program success. Using these elements to support Tier I instruction can lead to increased student achievement in mathematics at the middle school level. [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.]