The first secessio plebis was a significant event in ancient Roman political and social history that occurred between 495 and 493 BC. It involved a dispute between the patrician ruling class and the plebeian underclass, and was one of a number of secessions by the plebs and part of a broader political conflict known as the conflict of the orders.

The Mons Sacer, Sacer Mons, or Sacred Mount is a hill in Rome, famed as the location of the first secession of the plebs, in 494 BC.