Transnational surveillance is a powerful tool in the arsenal of autocrats the world over. Despite its pervasive use in extraterritorial coercion, the systematic study of surveillance of regime opponents beyond national borders remains underdeveloped in political science, primarily due to limited data availability. To help fill this gap, we constructed the Latin American Transnational Surveillance dataset, a micro-level dataset based on declassified foreign surveillance reports produced between 1966 and 1986 by autocratic Brazil. Latin American Transnational Surveillance records the identity, locations, social ties and political activism of 17,000 individual targets of transnational surveillance, the vast majority of whom were tracked in neighbouring countries across Latin America. Drawing on these abundant data, we empirically explore existing theoretical insights about the motivations, methods and consequences of transnational surveillance, a task that would be difficult to do using other sources. We also leverage social network analysis to showcase potential applications of Latin American Transnational Surveillance in the testing of collective-action theories of transnational political violence.