The Southern Atlantic city of Buenos Aires emerged a critical hub of radical political activism between 1916 and 1930 at a time when the influence of anarchist activists waned and organized labor often worked with the Radical Civic Union presidents. Whether based in or passing through this city, activists and exiles, partisans, and pretenders pursued various strategies to achieve revolutionary change, raise funds for causes, assure sovereignty, control the public narrative, and network with like-minded individuals and groups. These agitators created webs of associations throughout the Atlantic world in the process. These networks were vital in fashioning enduring transnational connections, strategies of resistance, shared discourses, and symbolic registers that framed how nationalist and anti-imperial interactions were understood. This article focuses on Irish republicans, Catalan nationalists, and Arab anti-colonialists and their interactions with Argentine agitators, sympathizers, and various state actors to more fully understand the importance of Buenos Aires in this period and the consequences on sociopolitical life in this Atlantic port city up to the global depression of 1930.