This research addresses the problem of low math achievement of middle school students through the use of a Growth Mindset intervention and related strategies. While the research on Growth Mindset interventions and strategies show positive results in controlled settings, there is a need to better understand Growth Mindset implementation from the perspectives of teachers and students in classroom settings. This study looked at Growth Mindset implementation with 449 students and seven teachers in sixth-grade math classrooms from two middle schools in one suburban school district. This study examines teacher and student perspectives of the effectiveness of four Growth Mindset instructional strategies and achievement results after a Growth Mindset intervention conducted by the classroom teachers. Teachers learned to implement four Growth Mindset strategies through an online professional development series provided by the district and shared their perspectives in an online discussion group and subsequent survey. All the sixth-grade students completed a survey and the researcher conducted two focus groups to identify students' perspectives of the classroom goal orientation and the Growth Mindset strategies. The impact of the Growth Mindset intervention was measured using benchmark test scores and trimester grades, which assisted the district's goal to improve mathematics achievement in middle school. The results demonstrate that teachers and students perceive both mastery and performance classroom goal orientations and find two Growth Mindset strategies, celebrating mistakes and providing challenging math tasks, to be well received by both groups. Findings also indicate that after the Growth Mindset intervention student achievement on the benchmark test did not improve, however, students' grade point average did improve compared to students from the previous school year in the same district. [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.]