Background: Barriers to reforming traditional lecture-based undergraduate STEM classes are numerous and include time constraints, lack of training, and instructor's beliefs about teaching and learning. This case study documents the use of a situated instructional coaching process as a method of faculty professional development. In this model, a geoscience education graduate student (the coach) assisted a faculty member in reforming and teaching an introductory geoscience course on dinosaurs using evidence-based teaching strategies. The revision process occurred in three phases to progressively transfer responsibility for lesson design from the coach to the instructor over the length of the course. Data on instructional practices were collected using the Reformed Teaching Observation Protocol (RTOP), and belief changes experienced by the instructor were captured using the Teacher Beliefs Interview (TBI) and Beliefs about Reformed Science Teaching and Learning (BARSTL) survey. Results: RTOP data confirm that the instructor was successful in teaching the lessons as designed and also gained skills in designing reformed lessons. TBI and BARSTL were indicative of a shift in the instructor's beliefs toward a more student-centered perspective. Conclusions: Data collected on instructional practice and teaching beliefs indicate that this model served as an effective method of professional development for the instructor.