Despite her reputation as a reclusive poet, Emily Dickinson wrote more than one thousand "letters to the world," engaging in lively epistolary conversations with close to one hundred correspondents. Although these letters have found many avid readers since they were first published in 1894, they have often been viewed as mere background materials or vehicles for the writer's poems. This study offers a reevaluation of their status within Dickinson's canon, arguing for "correspondence" (rather than "poetry") as her central form of expression. Concentrating on Dickinson's exchanges with childhood friends, as well as with Susan Gilbert Dickinson, Elizabeth Holland, Austin Dickinson, Thomas Wentworth Higginson, and the mysterious "Master," Marietta Messmer explores the poet's gradual shift from writing confessional letters to developing her unique "vice for voices" by creating fictionalized epistolary personae. While radically challenging nineteenth-century letter-writing conventions, these personae also subvert the narrowly circumscribed roles available to women at that time. Messmer shows how Dickinson used this double-voiced mode of correspondence to manipulate and interrogate a variety of male-dominated, "authorized" literary, religious, and sociocultural discourses.