Marquette University, in collaboration with the University of Wisconsin La Crosse, proposes the PUMP-CS Project (Preparing the Upper Midwest for Principles of Computer Science). PUMP-CS will provide a two-track professional development (PD) sequence for endorsing in-service and pre-service teachers--regardless of their prior CS-specific knowledge--to teach the Exploring Computer Science (ECS) or Computer Science Principles (AP CSP) curricula in their classrooms. The first track prepares in-service teachers to lead 9th- or 10th-grade level ECS, which integrates an inquiry- and equity-based pedagogy to convey solid CS content while appealing to a more diverse student population than traditional CS offerings. The second track includes a methods course, Teaching Computer Science (TCS), which enables both pre-service and in-service teachers to add a CS-specific endorsement to their primary certification, while continuing to promote pedagogical reform. This CS methods course is a "missing link" preventing teachers from earning the CS endorsement required to teach a course with more than 25% programming content, (e.g. AP CS or CSP). The planned hybrid/online format for TCS will allow remote teachers in "density-challenged" regions to participate in a supportive learning community as they master the content and methods required. The project team includes members from universities, the Wisconsin-Dairyland chapter of the Computer Science Teachers Association (CSTA), officials from the Department of Public Instruction (DPI), and teachers and administrators from districts across the state. Collectively, they have the diverse institutional knowledge necessary to drive change in state licensure and curriculum standards, to match college-level courses at key universities to the STEM student pipeline, to promote new content and structure for CS teacher preparation, and to rigorously assess the results of this large-scale intervention on teacher education and student learning. This proposed work will lead to regional, sustainable institutional change to improve CS education, and scalable teacher preparation materials ready for other institutions to adopt, and its careful assessment will explore deeper questions of when and how CS teacher preparation can be most effective, and how those lessons can be leveraged in other STEM teaching fields.