Since the enactment of Every Student Succeeds Act (ESSA) in 2016, K-12 schools in the U.S. have responded to the challenge with various instructional reform initiatives. School climate, teaching practices, and teacher self-efficacy are important aspects of research as they affect students' learning. The purpose of this study was twofold: first, to evaluate the goodness of fit of the three hypothesized mediation models with the data from the Teaching and Learning International Survey (TALIS) using Structural Equation Modeling (SEM); and second, to determine the interrelations between teacher self-efficacy, school climate, and teaching practices. To address the research questions and hypotheses, U.S. national data with 2,560 teachers from 165 lower secondary schools (7th, 8th, and 9th grades) were used in the current study. The results indicated that (1) teacher self-efficacy significantly and partially mediated the relationship between school climate and teaching practices; (2) teaching practices significantly and fully mediated the relationship between school climate and teacher self-efficacy; and (3) school climate significantly and partially mediated the relationship between teacher self-efficacy and teaching practices. Theoretically, this study enriched the understanding of teacher self-efficacy by adding multicultural self-efficacy and the understanding of teaching practices by including diversity practices. Methodologically, using SEM to test the three hypothesized mediation models, this study provided the generalizability to other contexts and an example for future research using SEM to explore the topic using large-scale secondary data such as TALIS data. For practice, the current study provided implications on the interventions of school climate, teacher self-efficacy, and teaching practices. [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.]