The most obvious area in which the study of Ancient and Modern Greek complement each other is vocabulary. We present lists of correspondences between Ancient and Modern Greek vocabulary, including a study of formal and semantic relations between the vocabularies of four AG textbooks (used in USA and European countries) and Standard Modern Greek, distributing AG words into four different classes. In some cases knowledge of the Ancient language might cause interference errors (“false friends;” e.g. μάλιστα, συκοφάντης, etc. with different meanings in AG and MG). We provide a list of such potential interference errors, and strategies for avoiding them. We also briefly examine differences and continuities between word-formation principles in Ancient and Modern Greek.