Joint Interagency Task Force-South (JIATF-South) is well known within the U.S. Government as the "gold standard" for interagency cooperation and intelligence fusion, despite its preference for keeping a low profile and giving other agencies the credit for its successes. It is often cited as a model for whole-of-government problem-solving in the literature on interagency collaboration, and other national security organizations have tried to copy its approach and successes. Despite the plaudits and attention, the way that JIATF-South actually operates has only received superficial analysis. In fact, few people actually understand why JIATF-South works as well as it does or how its success might be replicated. This study attempts to fill the gap in knowledge about JIATF-South as a model for crossorganizational collaboration. It traces the evolution of the task force from its roots in the "War on Drugs" in the 1980s, through its original manifestation as Joint Task Force-4 in the early 1990s and its later reinvention as Joint Interagency Task Force-East (and still later, its renaming as JIATF-South), up until the present day. It then examines how JIATF-South actually works with the help of 10 organizational performance variables taken from organizational and management research on cross-functional teams. Investigating JIATF-South's performance through these different organizational lenses, and weighing the importance of each variable in light of JIATF-South's historical experience, yields a compelling explanation for JIATF-South's stellar performance. The results contribute to a better understanding of interagency teams and help answer the pressing question of whether successes like JIATF-South can be replicated elsewhere in the national security system.