Much of the scholarly attention toward black abolitionists in the British Isles has focused on celebrity lecturers in Britain. Yet Ireland was an important location for several black activists who helped shape the transatlantic abolitionist movement. The crowds at antislavery events are usually depicted as a faceless mass. Why they were drawn to these speakers as well as how they differed according to region, religion, and class is examined in detail below. Moreover, Daniel O’Connell and Frederick Douglass are traditionally viewed as nationalist heroes (Irish, Catholic, American, African-American, etc.) but this article illustrates the extent to which they also operated and were respected as committed internationalists. Douglass supported Irish independence. O’Connell advocated slave emancipation in the United States. In contrast to prevailing views of inevitable racial tensions between the Irish and Blacks, it traces a more internationalist consciousness through lectures, speeches, writings, public pronouncements, and popular reactions. The article seeks to illustrate the cross-border dimensions of emancipation as well as the utility of transnational historical analysis.