Teacher empathy has often been considered vital to successful and equitable teaching practices; however, empirical results have been inconsistent as to the effect of teacher empathy on educational outcomes. Further, researchers have questioned the effectiveness of both recent operationalization's of teacher empathy as well as its application in diverse classrooms. This multiple manuscript dissertation--in which I developed a conceptual framework for effective teacher empathy, developed an instrument to operationalize this conceptual framework using student perceptions of student-teacher interactions, and applied this measure to middle and high school mathematics students to examine its relationship to educational outcomes--is my attempt to address these gaps in the literature. In the first manuscript, I examined both historical and recent conceptualizations and measures of teacher empathy as well as pertinent critiques from researchers and developed a conceptual framework for effective teacher empathy. I further examined this conceptual framework as it may influence equitable teaching practices in middle and high school settings. In the second manuscript, I operationalized effective teacher empathy with an instrument assessing middle school student perceptions of interactions with their teachers. Results from this study provided strong evidence for this measure's validity and reliability in a middle school setting. In the third manuscript, I applied this measure to middle and high school mathematics classrooms and found that student perceptions of teacher instructional empathy predict math achievement through the mediation of self-efficacy. Additional results suggest student-teacher ethnic match among minoritized students may influence student perceptions of instructional empathy. Collectively, these studies examine the role of teacher empathy in middle and high school classrooms, particularly with a focus on supporting equitable teaching practices for diverse groups of students. In the final chapter, I examine the findings of all three manuscripts along with limitations as they pertain to future research and implications for teacher practice. [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.]