Equipment reliability is concerned with the risk of failures in equipment and processes, providing focus on equipment availability, fitness for purpose, and cost. The strategy and tactics of reliability contribute to realizing the value of equipment throughout its useful life and mission. Reliability and maintenance strategies are developed to reduce the risk and impacts of equipment failure. From a management perspective, reliability can be viewed as a set of techniques applied through an attitude of anticipating unreliability (instability) and an appreciation for the proactive elimination of issues. Reliable equipment improves the likelihood of achieving reliable operations and thus improves the supply of critical therapies to patients worldwide. This ISPE Good Practice Guide: Equipment Reliability intends to provide guidance on the application of equipment reliability concepts to systematically and proactively improve equipment reliability at all stages of the equipment lifecycle. This Guide is not intended to provide the basic body of knowledge for equipment reliability or reliability engineering. This Guide offers best practices with respect to equipment reliability, addresses specific opportunities for the pharmaceutical industry beyond the general reliability of equipment, and can serve as the basis for an effective reliability program.