Year 434 BC was a year of the pre-Julian Roman calendar. At the time, it was known as the Second year of the Consulship of Iullus and Tricostus or the Year of the Consulship of Capitolinus and Praetextatus and the Year of the Tribunate of Cossus, Praetextatus and Capitolinus (or, less frequently, year 320 Ab urbe condita). The denomination 434 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.