Mathematical learning is supported by caring teaching, which is complex, political work particularly for white teachers in racially diverse classrooms. To investigate white teachers' understandings of care and its influence on mathematics instruction, I conducted a six-month qualitative study in two racially diverse ninth-grade Algebra 1 classrooms, which were cotaught by two white teachers at a public high school. Primary data sources include daily classroom observations, teacher interviews, and student interviews. Based on prior literature and the resulting analysis, I theorize care in mathematics education along three dimensions: academic, social, and political. The academic dimension involves the technical aspects of mathematics instruction. The social dimension involves both the teacher-student relationship and teachers' actions to facilitate students' social connection with each other. The political dimension includes teacher criticality, their ethical use of institutional authority, and conversations with students about race. Findings demonstrate how the teachers' and students' narratives of schooling shaped their understandings of care along these three dimensions. I also show how the teachers' theories of care shaped their pedagogical priorities and choices, how their care shifted over time, and how students understood caring teaching in general and the teachers' care specifically. This study contributes theory regarding the political care of white teachers in racially diverse mathematics classrooms, including how political care shapes academic care, social care, and mathematics teaching. This study also demonstrates the importance of contextualizing teachers' theories of care to understand why teachers teach as they do, and it surfaces dilemmas of care warranting further attention in teacher education, professional development, and future research. [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.]