This report presents the results of the Occupational Safety and Health Administration’s (OSHA’s) “Lookback” review of the Agency’s Control of Hazardous Energy Sources standard, also known as the Lockout/Tagout standard. The standard, which is codified in OSHA’s general industry standards at 29 CFR 1910.14 7, establishes requirements employers must follow to disable machinery and equipment and to prevent the release of potentially hazardous energy during the servicing and maintenance of that machinery and equipment. The Lockout/Tagout standard requires employers to develop and implement lockout/Tagout programs and to train their workers to follow required procedures during servicing and maintenance work. “Lockout” refers to the practice of installing a lock on an energy-isolating device, such as a circuit breaker or shut-off valve, so that mistake will not energize the equipment. The term ”tagout” refers to the practice of attaching a warning tag to an energy-isolating device to warn employees not to energize the equipment until the warning tag has been removed. OSHA issued the Lockout/Tagout standard in 1989.