This study investigated Turkish Language teachers' posts in a Facebook group regarding professional development during an academic year. This study was designed to be a case study, which employed qualitative research methods. The teachers whose posts were the most relevant to professional development were selected among the three Facebook groups with the highest number of members. The teachers' posts shared during the 2019-2020 academic year were obtained by document analysis. We analyzed the data qualitatively with content analysis. The codes were processed and analyzed by using MAXQDA Analytics Pro 2020 program. The posts generated 393 codes, and the content analysis revealed 36 categories and six themes. We determined the frequency of the codes for each theme and category. The six themes were "Material," "Content Knowledge," "Teaching Process," "Other," "Official Process," and "Culture and Art" from the most frequent to the least frequent. Through the posts in a Facebook group, we determined codes that supported Turkish teachers' professional development and provided suggestions for online professional development.