Göksoy, Süleyman2020-04-302020-04-3020181392-0340https://dx.doi.org/10.15823/p.2018.02https://hdl.handle.net/20.500.12684/561The present research aimed to determine the professional development levels of teachers according to developmental supervision approach. Case study method from qualitative research methods was used in the data collection. Educators participated in the research state that the professional development areas of the teachers should be comprised of eight main areas. These areas defined by the educators are lesson preparation and planning, teaching-learning process (lesson), assessment and evaluation, professional development, communication, counselling, classroom management, projects and time management. Therefore, it can be indicated that the determined professional development areas of teacher should be prioritized in order to increase both educational quality and teacher performances. © 2018, Vilnius Pedagogical University. All rights reserved.en10.15823/p.2018.02info:eu-repo/semantics/openAccessCase study; Developmental supervision and professional development; TeacherArticle12911532Q4