The purpose of this mixed methods study was to evaluate the impact of a growth mindset theory (GMT) intervention on struggling 9th grade math students. The intervention consisted of training students on GMT concepts and teaching through four GMT strategies. This study examined the perspectives of the students through a survey about mistakes in math, their ability to change their own intelligence, acceptance of math challenges to benefit their progress and mastery goal attainment. The instructional delivery of the math content was changed to support the GMT learning environment. The sample included 169 remedial math students from the researcher-teacher's classroom. The independent variables consisted of a pre- and post-math assessment of attitudes toward math and belief related to GMT. The impact of the intervention was measured by comparing pre- and post-math assessments through EDAMS and the relationship of this change with the students' attitudes toward math, mastery versus performance beliefs, and GMT concepts. The findings demonstrate that there were significant gains made in the students' attitudes toward learning math and slight increases in math scores in the multiple-choice (t = -7.49) and math tasks (t = -4.62) were also revealed. Pearson correlations revealed a statistically significant positive association between the math multiple-choice test scores and the two learning constructs, efforts attitude toward math (r = 0.39) and goal attainment (r = 0.22). A hierarchical multiple regression analysis showed that students' attitudes related to effort when controlling for goal attainment and growth mindset explained 7% of the variation of student math assessment in the multiple-choice test. [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.]