The Liberation Army of the South (in Spanish Ejército Libertador del Sur, occasionally abbreviated to ELS) was an armed group formed and led by Emiliano Zapata which took part in the Mexican Revolution. The force was commonly known as the Zapatistas.

The Zapatistas were formed in 1910 in the southern Mexican state of Morelos. Zapata's main cause was land reform. Zapata became one of the major figures of the Mexican Revolution.

The Zapatistas originally aligned with Francisco Madero in opposition to the regime of president Porfirio Diaz, who was soon after overthrown in 1911. After Madero's regime, too, proved uncommitted to the cause of land reform, the Zapatistas turned against him. Fighting continued against the successive leaders Victoriano Huerta and Venustiano Carranza. Zapata's assassination in 1919 struck a mortal blow to Zapatistas, and the army slowly disbanded afterwards.