Strong, well-prepared school leaders are a well-known lever for improving student achievement and retaining teachers, but principal retention has received less attention even as principals are leaving at worrying rates. State leaders can help develop strong principals in their states by investing in evidence-based professional learning opportunities for current and future leaders, as Missouri, Delaware, and North Carolina have done. Their experiences highlight how statewide learning academies, mentorships, and peer-to-peer supports strengthen the principal pipeline and, in turn, build an effective educator workforce.