PK-12 leaders use gender- and sexuality-inclusivity professional development (IPD) as a tool to improve the school climate for LGBTQ+ students, but IPD programs vary widely in their scope, breadth, duration, instructional approach, and content. In this paper, we present the IPD conceptual framework, which proposes a sustained, intensive, and expansive approach to PD can influence student outcomes through changes in educators' beliefs, attitudes, skills, and knowledge concerning gender and sexuality. Using a large, Midwestern school district as a case study, we examine characteristics of schools participating in an intensive IPD program and whether participation contributed to school disciplinary rates. Using 2018-2019 administrative and program data from the district and state department of instruction, we: (1) describe demographic and program differences between IPD and non-IPD schools, and (2) evaluate the contribution of IPD on disciplinary outcomes using OLS regression analysis controlling for selection characteristics. Our analysis reveals less racial and ethnically-diverse and better financially-resourced schools participate in the IPD program. The regression analysis suggests schools participating in IPD have lower suspension rates, assault rates, and endangering behavior rates compared to non-IPD schools. Several studies indicate supportive leaders and IPD improves school climates for LGBTQ+ students; however, quantitative descriptions of how IPD may influence student behavior remain scarce. Policymakers and educational leaders may be interested in this study's results suggesting a decrease in disciplinary actions among schools committed to IPD with core components of the IPD framework.