Purpose: The purpose of this paper is to describe the variations in the ways that principals conceptualize their basis of power in schools. Design/methodology/approach: Phenomenography was used as the research method of this study. The interviewees consisted of 16 principals, eight from public schools and eight from private schools. Findings: The analysis of the interviews revealed eight ways of understanding a principal's power basis. These potential power bases were: teachers' sense of reciprocity; teachers' sense of responsibility; organizational rules and regulations; principals' deep knowledge and experience; in-service training; principals' reputation for being fair and impartial; teachers' sense of identification with their principal; and principals' control over teachers' employment. Participants from public and private schools held generally similar conceptions. The conception of in-service training remained limited to private school principals. The power basis of principals' control over teachers' employment was not emphasized but could still be perceived as a conception in certain statements by participants. Research limitations/implications: Coercive power and legitimate power of reciprocity need to be investigated more thoroughly in the field of educational administration. Practical implications: There is an urgent need for training for principals to raise their awareness of the adverse effect that coercive power has on teachers. Originality/value: This study is the first known to explore variations in the ways that principals conceptualize their power basis.