During the 1st millennium BCE, Greek language spread throughout Asia Minor, and its diffusion, which is reflected in a large number of local inscriptions found in different Anatolian regions, inevitably led to interactions, at different levels, between Greek and the epichoric languages of Anatolia. Such language contact resulted in several interference phenomena, both unidirectional and bidirectional, that can be observed not only in multilingual inscriptions, where they are most expected, but also in monolingual ones. Reflexes of such interactions are also found in Greek literary works, as well as in later scholarly sources, especially lexicographic ones of Byzantine times, among which a prominent role is played by Stephanus of Byzantium and Hesychius. This kind of evidence, traditionally referred to as glosses, is of special importance for the knowledge of the Anatolian languages themselves, because most of time they are languages of fragmentary attestation. Through a philological and linguistic analysis of such materials and a discussion on selected cases of language interference, this chapter will provide an overview of the role of the Greek language during the 1st millennium BCE in two particular regions of Anatolia, namely Lycia and Lydia, its interactions with the two Anatolian languages, together with the metalinguistic information retrieved from late Greek sources.