Year 428 BC was a year of the pre-Julian Roman calendar. At the time, it was known as the Year of the Consulship of Cossus and Cincinnatus or Cincinnatus and Atratinus (or, less frequently, year 326 Ab urbe condita). The denomination 428 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.