The current study examined the relationship between school effectiveness and teachers' demographic characteristics, organizational citizenship behaviors and stress, and the effects of teachers' demographic characteristics, organizational citizenship behaviors and stress levels on school effectiveness. Within the scope of the research, a causal comparison model was used and the opinions of 222 Turkish teachers who were working in the schools were evaluated. According to the results, school effectiveness was significantly and positively correlated with all dimensions of teachers organizational citizenship behaviors, and significantly and negatively correlated with stress. In addition, it was found that the demographic characteristics were not a significant predictor of school effectiveness but only the seniority variable was a significant predictor of school effectiveness and it was found that the stress and dimensions of organizational citizenship behavior were significant predictors of school effectiveness.