This paper details the history of key policy events in various countries that led to the global diffusion of detention practices during the last 30 years and assesses some of the motives that appear to have encouraged this phenomenon. In telling this story, this paper seeks to flesh out some of the larger policy implications of beyond-the-borders immigration control regimes. Just as offshore interdiction and detention schemes raise important questions about custody, accountability, and sovereignty, they should also spur questions over where responsibility for the wellbeing of migrants begins and ends. As this paper demonstrates, when it comes to immigration detention, all the answers cannot be found just at home.