This chapter discusses the philosophies and practices that drive the MSUrbanSTEM Leadership & Teaching Fellowship Program. This multi-year project offered a professional development program to three cohorts of K-12 STEM educators from Chicago Public Schools, one of the largest urban districts in the U.S. This chapter provides a holistic view of the program, focuses on the strategically developed curriculum and the theoretical bases for the chosen pedagogy. In addition, because the sustainability was an integral part of the program, the chapter describes the role of sustainability fellows. Finally, the authors provide some findings about the teachers' growth and development.