The purposes of the study are to explore the leadership styles of the school principals under Bangkok Metropolitan Administration and to find out whether their leadership styles were different according to gender, age, education, term of service and school size. One hundred and seven BMA school principals who responded to a mailed questionnaire were the subjects of study. The Fiedler Contingency Models leadership styles questionnaire was used to collect data. Data were analyzed using frequency, percentage, arithmetic mean, standard deviation and ANOVA (F-test). The findings were as follows: 1. Most of the BMA school principals were classified as relationship motivated leaders who perceived themselves as having high Situational Control. 2. When their leadership styles were considered along with high Situational Control, The BMA school principals leadership styles were assessed as being aloof, self-centered, somewhat autocratic and having poor group performance. 3. Gender, age, education, term of service and school size did not significantly influence principals leadership style elements in terms of the Least Preferred Coworker, Leader Member Relations, and Position Power. Term of service and school size did significantly influence principals perception of Task Structure at the 0.05 level, however. According to these findings, it is recommended BMA school principals be provided with leadership training so as to be more effective in their school management.