New teachers are leaving the profession at an alarming rate. To retain them, school systems need comprehensive supports and collaborative school cultures that help teachers navigate the complexity of learning to teach. This action research study investigated the problem of new teacher turnover within a school-university partnership context. The research was guided by one overarching question: "What is learned at individual, group, and system levels that advances theory and practice in the induction phase of teacher development in a school-university partnership context?" The purpose of the action research project was to design, implement, and evaluate programming that enhanced the school district's induction (new teacher) support program. A diverse action research team, including university faculty and school district administrators, led the study. Guided by complex adaptive system (CAS) theory and social network theory, the team collaborated with other educators to design two major interventions that were responsive to new teachers' needs during the Covid-19 pandemic. Interventions included a three-day virtual New Teacher Orientation (NTO) that built learning communities among new teachers and monthly professional learning sessions that built mentor teachers' capacity to help novices navigate the challenges of their first year of teaching. Both interventions prioritized relationship-building among educators and provided educators with instructional and emotional support. The study's findings show that new teachers benefited from opportunities to collaborate within group learning communities with educators who had a wide range of experiences. The study also found that school district and university partners built group social capital that resulted in innovative and impactful induction programming. Conclusions from this study suggest that educator collaboration within dense social networks must be placed at the forefront of P-12 education systems design. Social network theory-informed design can accelerate teachers' learning and growth and build their capacity to navigate systemic complexity. The study also concluded that school-university partnerships can be powerful tools for responding to the complex challenges P-12 school systems face, including new teacher retention. Partnerships bring multiple perspectives to common problems and create joint ownership for reimagining and transforming education systems into organizations where educators and students can grow and thrive. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]