The U.S. Navy requested over $40 billion each of the last 3 years to build, operate, and sustain its fleet. Acquisition decisions made as ships are developed and built can have a long-term effect on sustainment costs and ship quality. GAO was asked to assess the extent to which DOD considers and plans for sustainment when acquiring weapons. Among other objectives, this report assesses the extent to which: (1) Navy ship programs deliver ships to the fleet that can be sustained as planned; (2) the Navy develops and uses effective sustainment requirements during acquisition; (3) ship programs are effectively identifying and evaluating sustainment risks in planning documents; and (4) leadership considers programs sustainment planning and outcomes. GAO reviewed DOD and Navy acquisition policy and guidance, evaluated acquisition plans, collected sustainment metrics, and conducted interviews with more than 100 organizations, including program office and fleet units. GAO assessed 11 classes of shipbuilding programs (all nine that delivered warships during the last 10 years, as well as two newer classes of ships). GAO is making one matter for Congressional consideration to enhance oversight and 11 recommendations to help DOD and Navy improve ship sustainment. DOD concurred with 8 and partially concurred with 3 recommendations but did not describe specific actions, which GAO believes are necessary to improve sustainment outcomes.