The purpose of this mixed-methods study was to examine the relationship between teacher's perceptions of school climate and student achievement of middle school students. Two hundred twenty middle school teachers, from a large urban school district located in the Southwestern region of the US, participated in the "New Jersey School Climate Survey." Student achievement was measured using the Reading and Mathematics STAAR test. Data collected from the survey and interviews revealed that administrative support, building relationships, teaching and learning, and school safety are crucial factors that contribute to having a positive school climate. Because states are holding schools accountable for student achievement, and improving school climate, this study could provide significant contributions to school districts, administrators, and to the global discussion on the relationship between school climate and student achievement. [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.]