This book offers a history of mesmerism, or animal magnetism, in the antebellum (pre-Civil War) United States. Imported from the plantations of the French Antilles by founder Charles Poyen, established in New England textile-factory cities, and practiced throughout the US, mesmerism was surprisingly central to American life and to such canonical figures as Benjamin Franklin, Edgar Allan Poe, Herman Melville, Ralph Waldo Emerson, Margaret Fuller, and Nathaniel Hawthorne. It embraced a variety of phenomena, including somnambulism, mind control, spirit travel, and clairvoyance. Widely practiced from the 1830s to 1860, when it gave way to successor practices spiritualism and hypnosis, this occult science was understood by its practitioners as a way to make rational use of other people’s credulity, or tendency toward belief. The same predispositions that false priests had exploited to inveigle their devotees would now be made to serve modern ends, such as labor discipline, communication, and self-culture. Mesmerism thus poses a challenge to our ordinary view of secularization. Mesmerists neither rejected enchantment nor succumbed to it; instead, they managed it and exploited it in others. The history of mesmerism offers a fresh perspective on scholarly concerns related to modernity and the secular, such as colonialism, agency, the ideal of “empowerment,” and the place of belief. It shows us that modern enchantment is not a radical alternative or an atavistic throwback, but a target and a technique of management.