Many school districts have provided support to middle school mathematics teachers who face challenges involving delivery of instruction by hiring instructional mathematics coaches. The purpose of this qualitative case study was to explore the experiences between classroom mathematics middle school teachers and their instructional coach, and to understand how those interactions assisted in improving teachers' instructional practices. Vygotsky's adult learning theory formed the theoretical foundation of this study. The research question sought to understand the ways a mathematics coach helps teachers improve instruction. The convenience sample consisted of 6 middle school mathematics teachers and their instructional coach. Qualitative data were collected using semi-structured interviews to capture teachers' experiences with improving mathematics learning and classroom practice. Traditional qualitative analysis techniques were used to identify themes and understandings about the phenomenon of instructional coaching and the relationship between coach and teacher. Teachers reported improvement in their instructional practice as a result of (a) collaborative relationships, (b) embedded professional development, and (c) support within coaching. These data resulted in a staff development project intended to support teachers, administrators, and coaches as they develop local instructional coaching programs. This project study may create positive social change by improving interaction between classroom teachers and their instructional coaches. [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.]