A set of planning guidelines for multi-community command and control systems in law enforcement is presented. Essential characteristics and applications of these systems are outlined. Requirements analysis, system concept design, implementation planning, and performance and cost modeling are described and demonstrated with numerous examples. Program management techniques and joint power agreements for multi-community programs are discussed in detail. A description of a typical multi-community computer-aided dispatch system is appended. This document is one of a series of five guideline manuals on mobile digital communications, computer-aided dispatch, automatic vehicle location, patrol force allocation, and multi-community command and control systems for law enforcement applications.