Traditional forms of teacher professional development have generally not led to instructional change or improvement. Thus, innovative models of professional development are being explored to improve teacher quality and effectiveness. Content-Focused Coaching is a relatively new form of teacher professional development that incorporates content experts as coaches who lead teachers through coaching cycles consisting of a preconference where lessons are planned, an observed lesson, and a post-conference with debriefing and reflection, with the aim of improving instruction. The current study investigated the effectiveness of coaching cycles that incorporated the use of three defined coaching moves by a mathematics coach with three elementary teachers, as they designed and taught progressive elementary math lessons in their classrooms. A mixed method approach was used to collect data to examine the effectiveness of three coaching moves used by the coach during coaching cycles. Data were collected at three time points during each coaching cycles with each of three teachers. A total of nine coaching cycles were completed, three with each teacher. Data from a survey and transcripts of both the preconference meeting between the coach and the teacher as well as the lesson taught in the classroom were analyzed. The survey and the transcripts provided qualitative and quantitative data related to the effectiveness of the three coaching moves used by the coach during the coaching cycle. The results indicated a positive relationship between asking teachers deep and specific questions about the underlying math goals during the coaching preconference and the transfer of the underlying math goals to the classroom lesson. The results also indicated that when teachers are asked to write assessing and advancing questions for the solution paths students would use to complete the task, the students were given opportunities during the lesson to explain their mathematics reasoning and extend their thinking. Survey results indicated a positive response to the coaching cycle in that teachers found it to be an effective form of professional development that improved their instruction and content knowledge. While the results of this study cannot generalize the use of the coaching moves, they do add support to their effectiveness and at the same time add to the limited research on coaching, specifically effective coaching moves that result in instructional 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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]