It can be seen that school principals have taken a more active role in teacher supervision since regulations were put in place in Turkey in 2014. The research aims to understand the teacher supervision carried out by school principals through the school principals' evaluations. The 'case study' design, one of the qualitative research methods, is used in the study. The study group comprised seventeen school principals working at different levels in Zonguldak during the 2020-2021 academic year. The data collected with a semi-structured interview form was analyzed using the content analysis technique. According to the research, it is understood that the school principals see themselves as inadequate in terms of teacher supervision, they need in-service training on this subject, and they do not consider the supervision sufficient. School principals find their active role in teacher supervision positive; however, they are waiting for legal arrangements to be made that give them powers compatible with this role.