The purpose of this mixed method study was to explore the relationship among self-efficacy/beliefs, mathematical knowledge for teaching and student thinking. The study included 20 teachers who took a survey comprised of the Self-Efficacy for Teaching Mathematics Instrument (McGee, 2012) as well as the Mathematics Beliefs Scale (Fennema, Carpenter, & Loef, 1990). From this group, five teachers participated in a study that included professional development and coaching on the use of student thinking to guide instructional decisions. These five were also interviewed to further explore their efficacy and beliefs regarding teaching mathematics. In order to determine changes in classroom practice, observational data were collected using a Talk Moves Checklist (Chapin, O’Connor, & Anderson, 2009), the Levels of Engagement With Children’s Mathematical Thinking Scale (Franke, Carpenter, Levi, & Fennema, 2001), as well as the Math Talk Community Scale (Hufferd-Ackles, Fuson, & Sherin, 2004). These data were coded so that they were included with the other quantitative data from the survey and some parts of the interview. All quantitative data were collected before professional development began and than again when the professional development ended. Qualitative data collection came solely from the interviews. Recurring themes and ideas from the interviews were explored as they pertained to the research questions of the study. Data from the surveys did not show significant changes in teachers’ self-efficacy and beliefs as a result of participation in the professional development and coaching. However, other quantitative data as well as qualitative data did show changes in beliefs and classroom practice as a result of participation in the professional development and coaching portion of the study. Qualitative data also supported the idea that changes in practice, which were directly related to participation in professional development, occurred because of realized student success. This study offers information related to changes in teachers’ beliefs and classroom practice when coaching follows professional development. In addition, this study provides insight into changes in teachers’ beliefs and classroom practice when teachers see their students being successful with information learned in professional development.