This article explores John Stuart Mill’s career-long interest in federal models of politics. Demonstrating how multi-faceted Mill’s account was shaped by his views on civilization and empire, it argues that Mill was far more committed to federalism – as historical phenomenon, solution to contemporary political crises, and ideal for the organization of humanity – than is usually recognized. From his readings of ancient Greek history, through his reflection on the United States constitution, to his musing on the fate of Europe, federalism formed an important part of Mill’s account of politics, past, present, and future