A historian's lively and persuasive attempt to strip away the mystery surrounding the notorious 18th-century French cross- dresser, diplomat, writer, and spy, Chevalier (or ChevaliƤre) d'Eon. D'Eon was thought to be a man for most of his life. He was a distinguished soldier, diplomat, and confidant of King Louis XV's. He consorted with some of the most famous figures of his time—from Voltaire and Rousseau to David Hume and Benjamin Franklin. Then, when he was nearly 50 years old, he was ``revealed'' to be a woman. He lived the remaining 35 years of his life as a ``she,'' only to be proved, upon his death, a biologically ordinary man after all. The fascinating story of how and why he did it is examined by Kates (Trinity Univ.; The Cercle Social, the Girondins, and the French Revolution, not reviewed), who argues that d'Eon was neither a transvestite nor a transsexual, but rather a man who made an intellectual decision to cross the gender barrier based on his professional and religious aims. His diplomatic career had reached an impasse and he hoped greater opportunities might be made available to him as a woman; also he became increasingly religious, believing that women made better Christians and were morally superior to men. However, while the chevalier was successful in his masquerade and helpful in furthering women's equality, he was largely unsuccessful in his goals. D'Eon's career ended with his feminization, and the Revolution of 1789 stripped him of his government stipend; he died poor and relatively obscure. Overall a coherent story, though there are some missing pieces: the silence of d'Eon's mother and sister, who were alive during his gender transformation, is not sufficiently explained, and though he appears to have been a virgin his whole life, the question of d'Eon's sexual orientation is left unaddressed. Nonetheless, a wonderful window into 18th-century France and a valuable biographical study of a compelling historical figure.