This volume examines Third-Worldism as a heterogeneous, transnational field of political imagination, cultural production, and internationalist practice that emerged in the decades following formal decolonization. Conceived in the aftermath of the pandemic and renewed global reckonings with racism, this project revisits a historical moment when solidarity across continents appeared both possible and urgent. Rather than framing Third-Worldism as a predominantly European or Western phenomenon, this introduction highlights its multiple centers, actors, and ideological trajectories across the Global South and beyond. Bringing together scholarship on revolutionary networks, international law, Catholic and Marxist internationalisms, UN bureaucratic interventions, and anticolonial cultural production, the volume foregrounds the circulation of ideas between metropole and colony and the re-elaboration of decolonial projects within diverse local contexts. The chapters collectively show how Third-Worldism generated alternative visions of global order—at times emancipatory, at times compromised—while negotiating Cold War pressures, enduring colonial hierarchies, and internal contradictions, including patriarchal and epistemic asymmetries. Through studies of the Tricontinental movement, the right to development, postcolonial conferences, anticolonial literary networks, cinematic activism, and UN debates on ritual operations, the volume reframes Third-Worldism as a dynamic, contested constellation rather than a failed doctrine. Its afterlives, the introduction argues, remain vital for understanding contemporary struggles over internationalism, development, and decolonial futures.