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. 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.