Volume I of this critical edition of Shelley's prose--the first since the Julian Edition (1926-30)--provides authoritative texts of The Necessity of Atheism, the Irish pamphlets, the vegetarian essays, The Assassins, A Refutation of Deism, On Christianity, the "Hermit of Marlow" political writings, and several reviews. The texts, which are based on first editions and manuscripts, were all written between Shelley's last months in Oxford in 1811 and his departure for Italy in 1818. They are conservatively edited, with all changes from copy-text noted, along with revisions, deletions, and a historical collation of significant earlier editions. The Introduction provides a description of these editions, a full statement of editorial principles and practice, and an account of the relevant political and social context as Shelley knew and wrote about it. The commentary pays particular attention to the problems of dating the manuscripts, and contains more detailed copy-text descriptions, more thorough accounts of provenance, and more information on sources and allusions than any previous edition of the works. Location lists of rare first editions are comparably more complete than those provided in earlier bibliographies.