School climate can have a notable impact on student academic, social, emotional, and behavioral outcomes. It is also a critical component of school improvement efforts, as demonstrated by recent federal and state initiatives to provide resources and supports for increased school climate measurement, accountability, and improvement. The primary purpose of the current study was to establish measurement invariance of the Georgia School Climate Survey across gender and race/ethnicity among middle school students. The secondary purpose was to explore mean comparisons in school climate experiences across student groups. Participants included 629,584 middle and high school students. Confirmatory factor analyses supported a hierarchical model of school climate that included one overall factor, school climate, and eight subscales: school connectedness, civic engagement, physical environment, adult social support, peer social support, cultural acceptance, order and discipline, and safety. Measurement invariance for a subscale model of school climate across gender and race/ethnicity was established, and student means across groups were compared. Implications for the practical use of the GSCS as a school improvement tool to guide targeted and data-based decision are discussed.