It seems astonishing that one of the most important studies ever undertaken on Mozart should have taken almost eighty-five years to reach the English language. Hermann Abert’s monumental, and indeed famous, work was first published in 1924 and was originally intended as an updated edition to that other monumental work of Mozart scholarship undertaken by Otto Jahn, published in four volumes between 1855 and 1859. History appears to have repeated itself for the benefit of English speakers, with a fully revised and updated version of Abert’s text prepared by the Mozart scholar Cliff Eisen. A vast amount of historical and bibliographical material has been updated through informative and relatively unobtrusive footnotes, and one of the most comprehensive bibliographies on Mozart and his contemporaries ever assembled has been added. Stewart Spencer’s translation deftly preserves Abert’s original tone and grammatical idiom without a tortuous excess of Teutonic syntax.