This guidebook provides instruction for local leaders aiming to improve the efficiency of their justice systems by managing and allocating scarce resources more cost-effectively and generating savings that can be reinvested in prevention-oriented strategies. It describes the steps involved in this justice reinvestment process, the challenges that may be encountered, and how those challenges can be overcome. While the intended audience is local county and city managers and their criminal justice leaders, this document is designed to be accessible to a wide array of local government stakeholders, along with criminal justice practitioners, consultants, and researchers.