This mixed methods action research dissertation examines the effects of implementing growth mindset teaching practices in third grade math as a means to improve student math self-efficacy, math mindset and student achievement. Since the transition to the Pennsylvania Core Standards, students across the state including those in this district have been experiencing a decrease in math achievement in grades three through eight according to the Pennsylvania System of School Assessment (PSSA) the standardized achievement test all public school students take. Locally, traditional interventions such as worksheets, boxed programs, computer-based programs and extra practice have not yielded gains so this intervention focused on developing growth mindset teaching practices in math to answer four research questions. Framed in Dweck's Implicit Theories of Personal Attributes (1995), Bandura's description of self-efficacy (1997) and Hall and Hords' work with teachers in bridging research into practice (2011), this study used Jo Boaler's, "Mathematical Mindset" (2015) in a book study with the third-grade teachers. The dissertation study analyzed pre and post survey data from the third-grade class (n=57) on both mindset and self-efficacy. The study also analyzed pre and post survey data from the teachers (n=2) on mindset along with pre and post intervention interviews with the teachers. Qualitative and quantitative data analysis revealed the intervention had a positive effect on teacher mindsets and practices, a positive effect on student mindsets and a positive effect on student math self-efficacy. While the study did not reveal the intervention to have a positive impact on student achievement at this time, previous research included in the literature review cites improvement in student achievement through developing growth mindset thinking. This gives reason to predict that with more time, these students will experience improved achievement in math. Implications from this study include that we should train all math teachers in incorporating growth mindset practices, and that administrators should build the bridge between research and practice for teachers as they implement new teaching practices in effort to positively affect student performance. [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.]