Eurydice (c. 410–340s BCE) played a part in the public life of ancient Macedonia, the first royal Macedonian woman known to have done so. She was the wife of Amyntas III, the mother of Philip II (and two other short-lived kings of Macedonia), and grandmother of Alexander the Great. Her career marked a turning point in the role of royal women in Macedonian monarchy, one that coincided with the emergence of Macedonia as a great power in the Hellenic world. This study examines the nature of her public role as well as the factors that contributed its expansion and the expansion of Macedonia. Some ancient sources picture Eurydice as a murderous adulteress willing to attempt the elimination of her husband and her three sons for the sake of her lover, whereas others portray her as a doting and heroic mother whose actions led to the preservation of the throne for her sons. Both traditions describe her as the leader of a faction, as well as an active figure at court and in international affairs. Eurydice also participated in the construction of the public image of the dynasty. Archaeological discoveries since the 1980s enable us to better understand this development.