Publisher Summary There must be a formal method to deal with the change in the chemical industry. The safety designed into the original process often occurs after a multidisciplined design team has agonized for the optimum arrangement of process and layout. This process safety must not be jeopardized by modification schemes of poor quality. The exact approach used to scrutinize a proposed change must be site specific and developed for that location. Each chemical plant and refinery must adopt or develop a procedure tailored to fit the specific hazards, the available technical resources, the culture of the organization, and any governmental regulations. To ensure proper performance of the management of change (MOC) procedures, there must be periodic audits. The chapter provides an overview of MOC, along with beneficial insights and details. The chapter reviews various MOC procedures developed by major corporations. Key steps for the MOC system for a medium or large facility, as well as for a smaller organization are proposed in the chapter.