Functional requirements are based on the best practices of established information-sharing systems (ISSs). The functional requirements are either fundamental or optional. Fundamental requirements “must” be met and optional requirements enhance ISS functionality. Two key areas of functionality that are presented include: system architecture and data management and system capabilities. Operating an ISS involves the operation and management of the system to ensure that the ISS is accessed appropriately. Traditional forms of performance gauges, such as throughput and response time, reliability, availability, and scalability must be included. Also, maintenance, disaster recovery, and providing continuity of operations must be addressed. ISS requirements supporting these operational capabilities include: (1) user authentication, authorization, and access; (2) security; (3) system performance; (4) system support; and (5) training. When considering the implementation of an ISS, there are both programmatic and technical considerations. These considerations are necessary to ensure that the implementation of ISS functional and operational requirements results in a successful ISS. Programmatic considerations include governance, management, policy, and funding. Technical considerations are primarily associated with decisions regarding the type of architecture to employ, key system capabilities, origin of accessible data, and software rights. Agencies that have not yet developed an ISS can learn from the experiences gained and the lessons learned and adopt a strategy that works for them. This handbook is based on input from agencies that have experience with regional law enforcement information-sharing programs. It is one component of the Comprehensive Regional Information-Sharing Project (CRISP) effort to provide potential system developers with initial guidance to define functional and operational requirements for developing regional ISSs for law enforcement. CRISP is being conducted by Noblis’ Center for Criminal Justice Technology (CCJT) in partnership with the U.S. Department of Justice, National Institute of Justice (NIJ).