This guide from the Wallace Foundation and Policy Study Associates was created to support district leadership in preparing assistant principals for promotion to and success in the principalship. This resource includes guidance on forecasting principal vacancies, identifying assistant principals for the principalship, establishing and implementing a professional learning pathway for assistant principals, developing working plans, supporting success, and next steps. It is intended for use by those who develop principal leadership training opportunities; who have responsibilities in hiring or placement of school administrators; and who supervise, evaluate, and lead succession planning for school leadership.