<p>Although representational scaffolding has demonstrated positive effects on student learning in the inquiry-based learning environments, limited research has examined how teachers incorporate such scaffolding into their instructional practice. This study explores teachers’ adoption of representational scaffolding within a inquiry-based history project in a professional development intervention. Fourteen secondary history teachers collaboratively designed and implemented three scaffold-integrated lesson plans in partnership with a research team. Grounded in the Interconnected Model of Professional Growth, the study employed content analysis and epistemic network analysis to analyze teachers’ written reflections following each lesson. Findings reveal that teacher change happened over time in the mediating processes of reflection, as indicated by a temporal shift in teachers’ reflective focus—from initial attention to student responses to representational scaffolding toward more pedagogically oriented self-reflection. In contrast, no significant change was observed in the mediating processes of enactment. Teachers’ enactments of representational scaffolding within the inquiry-based history project appeared to be shaped more by their pre-existing beliefs and available external resources, rather than by learners’ learning outcomes. These findings provide evidence-based implications for the design of professional development initiatives aimed at supporting teachers’ integration of representational scaffolding in the inquiry-based learning.</p>