The purpose of this study is to investigate the effects of principals' autonomy, accountability, and teachers' empowerment on school organizational effectiveness. In order to accomplish this purpose, the study explored the differences of teachers' perception level on principals' autonomy, accountability, teachers' empowerment, and school organizational effectiveness. The study also analysed the correlations among principals' autonomy, accountability, teachers' empowerment, and school organizational effectiveness. Finally, the study examined the effects of principals' autonomy, accountability, and teachers' empowerment on school organizational effectiveness. The findings of the study are as follows: First, it was concluded that teachers' perceptions of principals' autonomy, accountability, teachers' empowerment, and school organizational effectiveness is above average, and the perceptions are higher in the case of experienced teacher with over 15 year, elementary school teacher, public school teacher, rural district teacher, and classroom size below 18 teacher. Second, it was found that there are significant positive correlations among principals' autonomy, accountability, teachers' empowerment, and school organizational effectiveness. All sub-variables of principals' autonomy and accountability, teachers' competence are correlated to teachers' job satisfaction and adaptability of organization, on the other hand, teachers' autonomy is correlated to teachers' job performance. Third, teachers' competence and impact highly affect overall school organizational effectiveness. Teachers' impact, principals' curricular autonomy, and teachers' competence highly affect teachers' job satisfaction, adaptability of organization, and job performance, respectively. These findings imply the importance of teachers' competence, teachers' impact, and principals' curricular autonomy as the factor of school effectiveness to lead changes and innovation in the school organization.