This article explores the connections between Chartism, the most important popular reform mobilization in nineteenth-century Britain, and the United States of America, a source of hope and inspiration for many British radicals of the period, by focusing on the ideas and publications of James Bronterre O'Brien. The article explains why Chartists admired America's political system and social condition, why Britain seemed to them to be so flawed and corrupt in comparison, and how O'Brien – Chartism's ‘schoolmaster’– used America in his political activities. Despite his key role in Chartism, especially in its early stages, O'Brien's reputation suffered thereafter, and among historians he has attracted only limited interest. His career merits another look. This article highlights in particular the ways in which he endorsed and increased the relevance of America to British radicals.