This study compares social studies teachers' and prospective teachers' pedagogical content knowledge in science, technology, and society learning. The study used the case study method, one of the qualitative research methods, and the holistic multiple case design of this method. The research participants are three social studies teachers working in Sakarya and four teacher candidates who are final year Sakarya University Education Faculty Social Studies Teaching students. Course observations, semi-structured interviews, and document analysis methods were used to examine the participants' pedagogical content knowledge. All collected data were transcribed and subjected to descriptive analysis in line with the predetermined pedagogical content knowledge components (subject content knowledge, curriculum knowledge, understanding of students, teaching strategies, and assessment themes). According to the findings obtained from the research, it was concluded that social studies teachers are more equipped than teacher candidates in terms of subject area knowledge and curriculum knowledge components in science, technology, and society learning. Both teachers and prospective teachers thought that students did not have much difficulty in science, technology, and society learning, and they followed specific strategies when students had challenges. All the participants were sensitive to the questions and reactions of the students and acted similarly in terms of understanding the students. Participants used methods such as lectures, and question-answers, and supported their lectures with various technological tools and materials. However, it was concluded that social studies teacher candidates apply different activities and use more materials in their lessons than teachers. Both social studies teachers and pre-service teachers used traditional learning tools while evaluating. There needed to be more in all participants in recording the evaluation results and giving feedback to the students. In line with the research findings, several suggestions were presented to improve the pedagogical content knowledge of teachers and teacher candidates.