This article aims to provide readers, especially those outside the U.S. Defense establishment, with an overview of U.S. Defense Institution Capacity Building (DIB), including its origins, key developments in the past decade, what it means in the U.S. context, who is responsible for its plan-ning and implementation, why the U.S. undertakes DIB, some of the chal-lenges U.S. DIB practitioners have faced to date, and finally a look at where DIB can be improved in the future.