Despite research documenting the potentially positive impacts of research-based instructional reforms in physics, few high school physics teachers in the US enact them. One of the more successfully disseminated reforms is Modeling Instruction. To discern aspects of this reform that afforded or constrained its dissemination, we analyzed the interviews of five people involved in the development of Modeling Instruction. Our findings are framed within theoretical perspectives from the communities of practice, diffusion of innovations, and leadership. © 2012 American Institute of Physics.