This study aimed to examine the effects of school principals' distributed leadership behaviors and teachers' self-awareness on school effectiveness through the mediating role of democratic practices and attitudes towards sustainable development in schools. Accordingly, an integrative model was created. The study data were analyzed using structural equation modeling and bootstrapping tests. The analysis results confirmed that organizational democracy played a prominent mediating role between school principals' distributed leadership practices and teachers' perceptions of school effectiveness. We also found evidence for the effects of school principals' distributed leadership behaviors and teachers' self-awareness on school effectiveness through the mediating role of teachers' attitudes towards sustainable development. We concluded that school principals' distributed leadership practices could enhance school effectiveness through teachers' perceptions of organizational democracy and attitudes towards sustainable development in schools. Besides, a high-quality educational environment and school effectiveness could be promoted by increasing teachers' self-awareness and attitudes towards sustainable development.