The main goal in this study was to explore the impact of a professional learning community (PLC) on social studies (SS) teachers' professional development (PD) and student academic achievement. With this in mind, the study was carried out using a design-based research approach with an overarching ADDIE design model. The participants of the study consisted of six SS teachers from two middle schools and 113 students. Data were collected using scales, observations, and semi-structured interviews and analyzed through qualitative techniques on teacher data as well as t-tests on student data. Findings suggest that the PLC designed in a reflective thinking cycle has had a positive impact on teacher PD and enhanced student achievement in SS. The conclusion is that there is a positive relationship between teacher participation in the PLC and student achievement. Therefore, it is recommended that the PLC be made widely available in PD of SS teachers, and PD programs be planned as long-term hands-on training activities, while also taking into account the specific needs of the field.