Given the mixed evidence on the role of school-level factors in contributing to racial inequality in exclusionary discipline, there is a need to revisit how the demographic composition of schools relates to the prevalence of and disparities in disciplinary outcomes. In this study, we extend the racial threat theoretical framework by illustrating the associations between racial composition and changes in the racial composition of schools and school-level disciplinary outcomes, such as rates of and disparities in office discipline referrals (ODRs) and suspensions, and student-level disciplinary outcomes, such as the likelihood of receiving an ODR and suspensions in New York City Public Schools. Similar to most prior studies, the findings indicate a significant association between the proportion of Black students in a school and overall suspensions and ODRs at both the school and student levels. At the school level, racial change in all other student groups except Black students is not significantly related to disciplinary outcomes. Our findings illustrate that a change in the percentage of Black students at a school is associated with an increased likelihood of receiving an ODR and suspension. Racial threat may be more pronounced in predominantly White schools compared to majority Black schools. The findings suggest that school climate, educator ethno-racial diversity, and principal experience moderate the relationship for school racial composition, with suggestive but inconsistent evidence for racial change. The results provide empirical evidence of anti-blackness in school discipline and support investments in school climate and educator diversity to disrupt discipline disparities.