OBJECTIVE: Failure to implement lockout/tagout (LOTO) procedures adversely affects the rate of work-related fatalities and serious traumatic injury and is one of the most frequently cited Occupational Safety and Health Administration standards. This study assesses the impact of a nationwide intervention to improve LOTO in small metal fabrication businesses. METHODS: Insurance safety consultants conducted a standardized and validated evaluation of LOTO programs and procedures. Businesses received a baseline evaluation, two intervention visits, and a 12-month follow-up evaluation. RESULTS: The intervention was completed by 160 businesses. The mean LOTO procedure score improved from 8% to 33% (P < 0.0001), the mean program score went from 55% to 76% (P < 0.0001), and the presence of lockable disconnects went from 88% to 92% (P < 0.0001). CONCLUSIONS: This nationwide intervention showed substantial improvements in LOTO. It provides a framework for assessing and improving LOTO.