Purpose: The purpose of this paper is to describe the various ways in which a group of principals conceptualize the power basis of teachers within teacher-principal interactions. Design/methodology/approach: The present study takes power as a potential to influence people as it was conceptualized in the taxonomy developed by French and Raven (1959/1968) and Raven (1993). This taxonomy was also used to discuss the conceptions emerged in the interview data. A total of 16 principals, 8 from public schools and 8 from private schools, were interviewed. Findings: The phenomenographic analysis of the interviews with the 16 principals revealed five ways of understanding teachers' power basis. These conceptions (in the form of categories of description) were: (a) the principal's sense of reciprocity, (b) teachers' field-specific knowledge, (c) teachers' administrative experience, (d) teachers' union affiliation and (e) teachers' legal rights. Categories (a) and (b) were common to all the study's participants. Category (c) was unique to participants from private schools, while categories (d) and (e) were unique to participants from public schools. Research limitations/implications: Three topics -- the subtler forms of legitimate power, the issue of teacher tenure and the influence of unions on the educational system -- appeared to have potential for interesting future studies in the field of educational management. Practical implications: There is an apparent need to include social power as a course component in preparatory programs for educational administrators. The revised power taxonomy, which took its final form after the revisions made by Raven (1993), appeared to be an adequate explanatory theory to understand the teachers' bases of power, and as such, it can be used to structure the content of the course about power interactions in school settings. In addition, the Turkish Ministry of National Education should handle the issue of unions' improper influence over the educational system and take necessary measures in order to maintain the effective functioning of public schools. Originality/value: To date, subordinates' bases of power as a research subject has apparently been ignored. The present study is the first to reveal variations in the ways that school principals conceptualize teachers' basis of power. Although the study data were collected in one city in Turkey, the research implications drawn from its findings can inspire interest in this neglected field of study all around the world.