Catharine Macaulay represented everything the eighteenth century abhorred in a woman. She was learned, politically minded, actively engaged with public and philosophical issues of the day. Her private life, and especially her `imprudent' second marriage to a man twenty-six years her junior,led to much malicious gossip. Yet in her lifetime she also won considerable fame. The author of an eight-volume history of England in the seventeenth century, a republican, a follower of John Wilkes, and a political polemicist, not only did she influence the nature of eighteenth-century radicalismin England, but she played an important contributory role in the shaping of American revolutionary ideology.Long before the Revolution she was also closely concerned with events in France. Both Mirabeau and Brissot were familiar with her History and much influenced by it; translated into French it was welcomed by patriots as an effective response to the counter-revolutionary influence of Hume's history.This is the first major biographical study of this remarkable and influential figure. For a woman to make such an impact in the restrictive environment of eighteenth-century England was astonishing: no one interested in the development of English radicalism or revolutionary politics can afford toignore Catharine Macaulay.