Shelley was a prolific and varied writer of correspondence throughout his short life. The work of collecting, editing, and annotating Shelley’s letters has been going on since the 1840s, but large portions of his early and Italian correspondence remain lost. The essay discusses this corpus and its critical history before examining three types of letters that Shelley was particularly adept at writing. Shelley’s adversarial letters to older men such as his father show his mastery of a radical bombast; correspondence with contemporaries such as Hogg and Hitchener shows him harnessing the form for the debate of ideas; and his long descriptive epistles about Italy, addressed to his friend Peacock, constitute some of the finest travel writing in English. T. S. Eliot was quite wrong to claim Shelley’s letters are ‘insufferably dull’: this essay begins to think about the elements of their content and style that reveal their literary achievement.