An independent external audit of the U.S. Department of Energy (DOE) Office of Legacy Management (LM) Environmental Management System (EMS) was conducted the week of June 4–7, 2018. LM successfully passed the audit with no negative findings and will be able to declare conformance with the new International Organization for Standardization (ISO) 14001:2015 standard. Although LM is required to have an EMS in accordance with DOE Order 436.1 (Departmental Sustainability), DOE program offices were asked in 2016 to implement and deploy formal environmental management systems and to declare conformance to the new ISO 14001 standard by October 1, 2018. The EMS is unique in DOE in that it is a joint federal and contractor program that covers the 100+ sites and offices LM manages across the U.S.