Previous studies have reported high attrition rates in large-enrollment science courses where teacher-centered instruction was prevalent. The scientific literature provides strong evidence that student-centered teaching, which involves extensive active learning, leads to deepened learning as the result of effective student engagement. Consequently, professional development initiatives have continually focused on assisting academics with the implementation of active learning. Generally, higher education institutions engage faculty in professional development through in-service workshops that facilitate learning new teaching techniques in a specific context. These workshops usually do not include self-scrutiny concerning teaching or do they provide continuous support for the implementation of strategies learned in the workshop. The purpose of this study was to explore the influence of a professional development program that consisted of a workshop focused on the implementation of active learning in large science courses and extended to include post-workshop activities, on participants’ enactment of teaching practices introduced in the workshop. More specifically, through a qualitative methodology and employing transformative learning theory, this work evaluated the influence of science instructors’ engagement in dialogue and critical self-reflection on their teaching approaches and practices. Engagement in critical reflection was facilitated through watching of teaching videotapes followed by participants’ engagement in dialogue about teaching with the researcher. Findings suggest that providing continuous post-workshop support by fostering engagement in critical self-reflection and dialogue, can lead to transformative learning about teaching. More specifically, participation in the program led to the transformation of teaching practices, while teaching approaches remained unchanged. While some obstacles to the transformation of teaching approaches were identified, major outcomes indicate that meaningful professional development can go far beyond learning how to use new teaching strategies through faculty engagement in critical reflection and dialogue on teaching.