Darkover inhabitants use a number of different languages, the variations in language is due primarily to the difficulty of traveling across the planet in part because of climate, terrain and minimal technology. There are two major languages spoken on Darkover and those are Casta and Cahuenga. There are nine languages spoken on Darkover, most of whom have their roots in English, Spanish and Gaelic.
In the Dry Towns they speak pure Gaelic. (The Heritage of the Hastur)