This document is Theresa Ann Costa Johansen's doctoral dissertation examining teacher-level factors that influence student discipline decisions. It provides background on zero tolerance policies and their links to increased exclusionary discipline practices. Exclusionary discipline has been associated with negative student outcomes. The study aims to understand how teacher perceptions of self-efficacy, collective efficacy, student behavior, and school climate relate to classroom and schoolwide discipline practices. It uses mixed methods to gather data from a California middle school on discipline rates and teacher surveys and interviews. The goal is to provide insight into how teacher and school factors may influence discipline practices and student outcomes.