Shiraz University Teaching English as a Second Language Quarterly 2981-1546 45 3 2026 06 01 Action Research as a Catalyst for Empowering EFL Teachers' Pedagogical Content Knowledge 47 69 8595 10.22099/tesl.2026.54563.3457 EN Abolfazl Ghasemzadeh Department of English, Isf. C., Islamic Azad University, Isfahan, Iran Ehsan Rezvani Department of English, Isf. C., Islamic Azad University, Isfahan, Iran Fatemeh Karimi Department of English, Isf. C., Islamic Azad University, Isfahan, Iran Journal Article 2025 10 16 <strong>As teachers' professional development is pivotal to enhancing educational outcomes, the role of action research (AR) in advancing Iranian EFL teachers' pedagogical content knowledge (PCK) has yet to be fully realized, particularly within a social constructivist framework. In light of this gap, this study aims to explore the impact of socially constructed AR on the PCK of eight in-service Iranian EFL teachers, with a particular focus on the transformative power of reflective practice and collaborative learning. To achieve this, a sequential explanatory mixed-methods design was employed. Data were collected through pre- and post-intervention questionnaires, alongside semi-structured interviews and observational field notes that offered a perspective on teacher experiences. The results indicated statistically significant improvements in teachers' PCK, though with modest effect sizes. Qualitative insights revealed heightened instructional confidence, increased student-centered approaches, and enriched collaborative learning experiences. However, institutional barriers such as limited time and support hindered the full realization of AR's potential. No significant gender-based differences in knowledge gains were observed. This study underscores AR's perceived potential to foster reflective teaching and enhance PCK among Iranian EFL teachers. </strong><strong>The study concludes that institutional support, including professional learning communities, is needed to sustain AR initiatives. It recommends longitudinal research to assess AR's long-term impact and urges integrating AR into teacher development frameworks for sustainable growth.</strong> https://tesl.shirazu.ac.ir/article_8595_d0a8e63507085c17b55c719e7c8e1859.pdf