The selection of school principals is being conducted according to subjective evaluations rather than objective criteria. It cannot be sufficiently assessed in the hiring process whether the personality traits of school principals, who are the leaders of school communities, are appropriate for administrative functions. In addition, the administrative self-efficacy beliefs of principals need to be explored. This study looks into school principals' personality traits and administrative self-efficacy beliefs. The research draws its data from 643 school principals in Ankara. The findings show that school principals have high self-efficacy beliefs and conscientiousness and they are extrovert. Canonical correlation analysis reveals that personality traits predict 60% of principals' administrative self-efficacy beliefs. Based on these findings, it can be concluded that principals hold self-efficacy beliefs which help them to achieve managerial tasks. Personality traits play a vital role in the emergence of these beliefs.