This article introduces the US Aid to Security Sector Actors (USASSA) dataset, the product of a collaboration between academic researchers and the nonprofit Security Assistance Monitor. In addition to providing the most comprehensive source of data on US security assistance, the USASSA dataset transforms detailed information about how security assistance funds are spent into aid and recipient typologies that can be used to conduct more sophisticated analyses of how this foreign policy tool is employed, its utility, and its limitations. Our data clearly show not only the magnitude and geographic reach of US SSA, but also its diversity. While some SSA is akin to humanitarian aid, other types of assistance blur the line between foreign aid and proxy warfare. We demonstrate the utility of the dataset’s typology of aid types with an analysis of factors affecting variation in the amount and type of aid provided to different states.