What a remarkable year of achievement and progress for the Department of Energy’s National Nuclear Security Administration! From flight qualification tests of the B61-12 in the Nevada desert, to removals of highly enriched uranium in Ghana and the Republic of Kazakhstan, to the commissioning of a new class of nuclear-powered aircraft carrier, NNSA lent its world-class expertise in the military application of nuclear science to help keep the United States safe and secure. This Year in Review outlines NNSA’s key accomplishments in 2017 across its core missions of maintaining the U.S. nuclear weapons arsenal, reducing the threat of nuclear proliferation and nuclear terrorism, and powering the nuclear Navy. It also highlights progress on modernization of NNSA’s aging infrastructure and continued investment in NNSA’s greatest asset, its people. After all, the success of NNSA is a direct reflection of a remarkably talented workforce dedicated to national security.