Appalachian State University (AppState), partnering with the Friday Institute of Educational Innovation at North Carolina State, proposes a project -- CS4App: Bringing Computer Science to High Schools in Rural Appalachia -- to expand and diversify Computer Science (CS) education in rural high schools. The project will gain insight into the obstacles to CS education faced by high school students living regions such as Appalachia with high rates of poverty, and it will develop a comprehensive program to prepare and support their teachers in teaching an AP Computer Science Principles (CSP) course.<br/><br/>CS4App will develop a Networked Improvement Community (NIC) partnering AppState faculty and regional teachers with an interest in offering CSP at their school. The Friday Institute will deliver an effective blend of research-based teacher professional development (PD) including a 4-week, intensive training in the summer and continued interactions during the school year. The PD will introduce CS technical and pedagogical content, as well as leadership development, inquiry-based instruction, and student equity issues.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.