An increasingly popular way of supporting teachers is with instructional coaching, which involves the teacher working alongside an instructional coach in the classroom and participating weekly in professional development. Due to a challenge issued to educators from government leaders, schools and districts are considering the coaching model as an alternative type of professional development to enhance math instruction; however, the expense of hiring an instructional coach has inhibited the buy-in of this service, particularly without empirical evidence to rationalize the cost. This qualitative case study in a metropolitan city in the southeastern United States focused on the effectiveness of the coaching program in order to justify its cost. The theoretical base for the study was Knowles' andragogy theory and Piaget's theory of cognitive development, both of which addressed the process of adult learning. The guiding research question for this study explored how professional development provided by the math coach affected the elementary teachers' instructional practices. Qualitative data were collected via questionnaires, interviews, and archival data. The analysis and coding of data revealed 5 major themes: creating instructional change, providing support, building confidence, navigating challenges, and increasing student achievement. Results indicated that the teachers perceived the coach's feedback to be supportive and positively impactful of their instructional practices. This study's findings can help school leaders identify and implement effective professional development components, including collaboration, model lessons, and locating resources, which will assist teachers in improving math education for elementary students and promote positive social change. [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.]