The issue of national identity in ancient Greece played an important role during periods of war due to the absence of a unifying political authority. Ancient Greece was organized along the lines of independent city-states with different political systems. However, in two wars, they were able to unite to combat a common enemy of Greece. In the Greek-Trojan War, the Greeks were the aggressors, and many Greek city-states responded to the call for joint action. In the Greek-Persian War, the Greeks defended their homeland. Once again, the Greek city-states, primarily Athens and Sparta, joined forces to repel the Persian invasion of mainland Greece. Homer, in his Iliad, and Herodotus, in his Histories, provide definitions of what Greek national identity was all about. By the time of the civil war, i.e., the Peloponnesian War, there appears to be a paradigm shift in what constitutes Greek national identity. The best definition within the context of this paradigm is given by Isocrates. This paper examines the national identity of Greeks as proposed mainly in the works of Homer, Herodotus, and Isocrates. It also explores the 19th-century controversy regarding whether modern Greeks have the same national identity as their ancient counterparts. Keywords: national identity, education, Homer, Hesiod, Herodotus, Isocrates, virtue, ancient Greeks, modern Greeks.