Since 2020, the state of Iowa has required all school districts to create and implement a plan for "high quality" computer science access at all levels of the K-12 curriculum. Because of this, an increasing number of school districts are asking one or more of their high school teachers to transition, at least part time, to teaching computer science. This research-practitioner partnership between the University of Northern Iowa and Iowa's nine Area Education Agencies (AEAs) builds on prior work to provide professional development pathways for teachers interested in pursuing full endorsement-level training. The project will promote the progress of computer science education by increasing access to participation in the partnership to teachers from across the state of Iowa, regardless of their geographic location. The combination of resources from the university and the AEAs will benefit teachers by providing academically rigorous instruction in both computer science and educational pedagogy, as well as a much-needed, peer based, localized, support network. The results of the partnership will include an increased number of highly-qualified and state-endorsed computer science teachers and a new professional development model that could be adapted for use by educational organizations around the country.<br/><br/>This award supports the scale-up of previous work conducted by the University of Northern Iowa Partnership for CS Teacher Preparation. In order to meet the goals of this award, the partnership will work with approximately 18 AEA personnel and 150 classroom teachers participating in two phases over a roughly three-year period. Each of these participants will complete the coursework necessary to earn Iowa's CS endorsement and, in the process, become well-prepared to teach a high-quality introductory programming or CS Principles course. Participants will become familiar with engagement practices and culturally-responsive computing through modeling and explicit instruction. Partner district support personnel will attend a Broadening Participation workshop to learn about biases and to formulate district goals for building a more positive school environment. By the end of the project, six of the nine state AEAs will have hosted a cadre of participants, and the RPP will be well-positioned to launch a truly statewide network for CS Teacher Preparation.<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.