Modeling as a scientific practice in K-12 classrooms has received a wealth of attention in the U.S. and abroad due to the advent of revised national science education standards. The study described herein investigated how a group of high school chemistry teachers developed their understanding of the nature and function of models in the precollege classroom through participation in a yearlong professional development program designed using model-based inquiry (MBI) as a framework. Further, we sought to understand the factors that catalyzed or hindered the incorporation of this pedagogy into the participants' classrooms. It was found that the program positively influenced the teachers' understanding of modeling as a scientific practice and facilitated growth in navigating pedagogical and conceptual challenges towards implementing modeling practices in their classrooms.