The mathematics classroom learning environment is often evaluated using numeric scores collected on standardized assessments. Research examining mathematics classroom environments and teacher practices has focused on ways to improve scores on these assessments. In contrast, this study centered on exploring teacher perspectives on creating classroom environments to support student growth beyond test scores. Qualitative case studies of four experienced high school mathematics teachers provided interview data to explore the concept of positive supportive classroom cultures teachers created for students. The cases showed the teachers' intentions and actions that built culture and supported student learning in their classrooms. Findings revealed teacher professional communities influenced their classroom communities. The teachers valued organic collaboration among their peers. In their classrooms, the teachers created a climate of collaborative learning and engaged students as contributors. The teachers took pride in the cultures they created and had clear perspectives about the effects of the cultures on their students. Teachers noted the cultures they created supported three areas of student growth: students feeling safe in the classroom to ask questions and describe challenges, students improving their confidence through social comfort working with peers, and students showing improvement in self-confidence in learning, both in mathematics and in school overall. Three appendices are included. [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.]