Educational groups, as one of the key mechanisms for teachers’ professional development, play an effective role in enhancing educational quality and improving teaching–learning processes. The present study aimed to analyze the effectiveness of educational groups in the Education Organization of Semnan Province, identify the challenges and barriers affecting their performance, and propose strategies for improving the effectiveness of these groups. This study was conducted using a mixed-methods approach with a sequential explanatory design. In the quantitative phase, the statistical population consisted of all primary and secondary school teachers in the Education Organization of Semnan Province, from whom 195 teachers were selected through cluster sampling. Data were collected using a researcher-developed questionnaire based on the Oliva and Pawlas (2004) model and were analyzed using descriptive and inferential statistical methods. In the qualitative phase, the statistical population included educational group leaders, school administrators, educational experts, and teachers associated with educational groups, from whom 15 participants were selected through purposive sampling. Data were collected through semi-structured interviews and analyzed using thematic analysis. The quantitative findings indicated that the effectiveness of educational groups was below the expected criterion level, and the professional leadership and evaluative roles demonstrated weaker performance compared with other dimensions. The qualitative findings identified two overarching themes as the main challenges affecting the effectiveness of educational groups: “the gap between educational policymaking and the actual needs of the educational field” and “the reduced effectiveness of professional interactions within the structure of educational groups.”