This systematic review by the American Educational Research Association’s Review of Educational Research examines the scientific landscape of critical thinking in teacher education. Drawing on 208 studies from around the world, the review synthesizes how critical thinking has been conceptualized, defined, and investigated across teacher education research. It finds that the field is highly diverse across educational levels, subject areas, geographic contexts, and research methodologies. The review also concludes that most studies adopt conceptions of critical thinking centered on analyzing claims, evaluating evidence, and drawing inferences, yet many provide only implicit or inconsistent definitions and use varied terminology, making the construct difficult to define consistently. The authors argue that this lack of conceptual clarity has important implications for teacher preparation and suggest that educator preparation programs should intentionally design coursework that explicitly connects critical thinking to disciplinary knowledge rather than assuming candidates will develop these understandings independently.