Building on reflective practices and action taking as cornerstones of teacher education and professional development, we argue that epistemic reflexivity becomes a powerful tool for teachers to facilitate meaningful and sustainable change in their classroom teaching. In this introductory article, we provide an overview of epistemic reflexivity conceptualized in the 3R-EC Framework, briefly review key theories in teachers' personal epistemologies, and introduce the four core articles that compose this special issue entitled "Changing Epistemic Cognition in Teaching and Teacher Education: A Focus on Reflection and Reflexivity." Finally, we anticipate conceptual, empirical, methodological, and educational opportunities that arise from the 3R-EC Framework.