The job of the school principal has become much more complex and demanding over the past several decades. Many university-based principal preparation programs-which prepare the majority of school principals-have struggled with how to make the fundamental changes needed to prepare principals for today's schools. To test a path forward, The Wallace Foundation provided grants to seven universities and their partners to redesign their principal preparation programs in line with research-supported practices. This report shares findings from the RAND Corporation's five-year study of The Wallace Foundation's University Principal Preparation Initiative (UPPI). Under UPPI, each team developed a clear and ambitious vision for its program. Overall, the changes the teams enacted ensured that the programs were more rigorous, coherent, and authentically connected to the work of on-the-ground school leaders. Throughout the initiative, the teams balanced common objectives and structure with flexibility for their specific context and changing conditions. This report illustrates that it is feasible for universities-in partnership with high-need districts, state agencies, and with the support of mentor programs that have engaged in successful redesign-to improve principal preparation programs to reflect the best available evidence.