Year 378 BC was a year of the pre-Julian Roman calendar. At the time, it was known as the Year of the Tribunate of Medullinus, Fidenas, Lanatus, Siculus, Pulvillus and Macerinus (or, less frequently, year 376 Ab urbe condita). The denomination 378 BC for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.