Background.Research examining the role of (in)equitable school climate is a critical line of inquiry that may inform efforts to eradicate disparities in academic, disciplinary, and mental and behavioral health outcomes among Black youth in U.S. schools.Students’ perceptions and experiences of inequitable and unsupportive school climate may explain in part why schools are so often ineffective in educating Black students.Disproportionate exclusionary school discipline practices are likely to exacerbate students’ inequitable experiences and disparate outcomes.Objectives.The purpose of this research is to explore theorized antecedents and consequences of inequitable school climate through the following specific aims: 1) to investigate whether differential experience of supportive relationships at school by race explain disparities in psychological outcomes; 2) to explore school organizational health and staff burnout as potential moderators of racial disparities in students’ experiences of equitable and supportive school climate; 3) to advance a dialogue on methodological and theoretical issues constraining research examining the contextual effects of school discipline disproportionality; and 4) to examine linkages between discipline disproportionality, inequitable school climate, and racial disparities in students’ peer relations and externalizing problems.Methods.In Aim 1, latent variable modeling was used to identify a theoretical model of inequitable school support and related engagement and social-emotional outcomes among Black and White high school students.Aim 2 used multilevel modeling to examine staff-reported school organizational health as a contextual moderator of racial disparities in Black and White students’ experience of equitable and supportive school climate.Aim 3 proposed guidelines and presented a research case study to advance a dialogue on the measurement and modeling of discipline disproportionality within a theory-driven, school climate oriented conceptual framework. Aim 4 employed multilevel modeling to examine the interaction of disproportionate disciplinary contexts with racial disparities in Black and White students’ social and emotional outcomes.Results.In Aim 1, racial inequalities in students’ experience of equitable treatment and caring relationships were identified. This differential experience of equity and caring at school explained racial inequalities in students’ sense of school belonging.Belonging, in turn, was more salient to Black youth’s emotional engagement and externalizing problems than it was for White youth, suggesting a pathway by which behavioral disparities may emerge.In Aim 2, school organizational health was significantly associated with both Black and White youth’s experience of equitable and supportive school climate; however, the association was stronger for White than Black youth, contributing to larger racial inequalities in students’ school experiences in schools with greater organizational health.In Aim 3 and 4, disproportionate disciplinary contexts were significantly associated with students’ perceptions of school inequity and with wider racial disparities in students’ peer relations and externalizing problems. Conclusions.Taken together, these four studies establish links between subjective and objective indicators of inequitable treatment and exclusion in high school and disparities in healthy developmental outcomes among Black youth.Our findings suggest that school-wide reform to promote equitable and culturally sustaining school climate should be a key target in our efforts to eradicate disparities in student outcomes.