This edition of the Servian commentaries on Aeneid 9-12 was originally conceived as the final volume of the so-called "Harvard Servius", begun by Edward Kennard Rand and his students at Harvard in the 1920s. Nearly a century farther on, the projects vicissitudes are too well known and too complex to bear repeating here: it is enough to say that this is the first new volume of the commentary to appear in over fifty years. On his death in 2013 Charles E. Murgia left publishable versions of the text, upper and lower critical apparatuses, and large parts of the introduction, and he had gather most of the data for the testimonial apparatus. Robert A. Kaster completed the work on the testimonia and introduction (using some of Murgia's unpublished writings to supplement the latter), added some subsidiary elements, and prepared the whole for publication. Thanks primarily to the work of Charles Murgia, this edition is superior to its predecessors in the same series, and to all other editions of Servius, in every respect.