Book IX of Herodotus' Histories provides the conclusion and climax to his work, as the victories at Plataea and Mycale complete the improbable Greek victory over Persia. The major themes of the work are all here echoed, modified, and revisited, and Book IX is thus essential for exploring its meaning (or range of possible meanings). This commentary, the first in English devoted solely to Book IX in over a century, treats Herodotus' work as both an historical narrative and a work of literature, incorporating the results of recent scholarly work in the fields of Greek history and historiography. It contains a Greek text together with detailed philological, literary, and historical notes designed to assist the intermediate and advanced Greek student. It will also be of use to graduate students and scholars.