In 1794, approx. 10,000 persons emigrated from Europe, esp. England, to the U.S. Many of them played an active role in the English radical movement that developed in the French revolutionary era, and were a vital component in the emergence of the philosophy that came to be known as Jeffersonian Republicanism. This study examines the career of one who was arguably the most prominent of all the political exiles from England at this time, the radical scientist, theologian, and political philosopher, Joseph Priestley. Contents: Priestley’s Decision to Emigrate to Amer., July 1791-April 1794; The Amer. Political Scene in 1794, and the Arrival of Priestley; Priestley in Northumberland, 1795-1797; Priestley’s Breach with the Federalists and Cobbett’s Attack, 1797-1799; Priestley’s “Letters to the Inhabitants of Northumberland” and the Election of Jefferson to the Presidency, 1799-1800; Priestley’s Final Years in Amer. under Jefferson, 1801-1804. Illus.