The purpose of this study is to examine the professional development of preschool teachers during summer holidays, and to develop recommendations for professional development between teaching semesters. The study is built on the basic interpretive design, with a study group of 24 preschool teachers. The data were collected through semi-structured interviews and were analyzed through content analysis. The content analysis revealed that summer holidays are basically seen as getting away from the profession and relaxation for preschool teachers, not as an opportunity for professional development. Preschool teachers found summer holidays unproductive in terms of their professional development. While the preschool teachers think that professional development activities should exist during the summer holidays, they believe that the current professional development system in Turkey does not make the idea very attractive and is considered to be efficient. The preschool teachers recommended that all professional development activities should fit with the needs of teachers, that both their personal and professional development should be supported, that holistic content should be created, that instructors specialized should be recruited, that learning methods fostering active participation and alternative assessment methods should be preferred, and that the expertise gained through professional development should be recognized, and rewarded. [This study was presented as an oral presentation at The Eighth International Congress on Curriculum and Instruction (ICCI-EPOK 2021), 25-27 March 2021, Burdur.]