Substantial research has established the connection between students' beliefs in a just world (BJW) and their perceptions of and behaviors in the school. While much of that research has acknowledged that the relationship between BJW and school variables must be bi-directional, little empirical evidence exists on how the school climate shapes students' perceptions of justice. This study draws from a comprehensive sample of Brazilian students from third through twelfth grade (n = 18,514) across 122 public schools in Southern Brazil. Results reveal that school climate variables account for 12.1-19.6% of the variance of students' BJW, with middle school being a time of strongest influence. Perceptions of rule fairness, student--student relationships, and positive and socio-emotional learning techniques were significant predictors across all grade levels. Additional analyses revealed that teachers' positive and socio-emotional techniques can act as a moderator between school climate and students' BJW. The results provide more tangible ways to integrate just world research into the educational context by bridging the gap between school climate research and just world theory. This study provides empirical data for the bidirectionality of BJW and school context and opens the discussion on how the school sets students' future expectations of justice.