The more people believe in a just world (BJW) in which they get what they deserve, the more they are motivated to preserve a just world by ones' just behavior. Consequently, we expected school students with a strong BJW to show less deviant behavior as cheating or delinquency. The mediating role of teacher justice was also examined. Questionnaire data were obtained from a total of N?=?382 German and Indian high school students. Regression analyses revealed that the stronger students' BJW was, the less cheating and delinquent behavior they reported. Moreover, the more the students believed in a just world, the more they evaluated their teachers' behavior toward them personally to be just, and the experience of teacher justice fully mediated the relation between BJW and cheating and delinquency, respectively. This pattern of results was in line with our hypotheses and consistent across different cultural contexts. It persisted when neuroticism and sex were controlled. The adaptive functions of BJW and implications for future school research are discussed.