There are four Acts in Diablo II, with an extra Act in Diablo II: Lord of Destruction. The player begins in Act I and moves through each Act in order as each one is completed (always ending in fighting a Great Evil). This is because the hero is tracking down Diablo, who visits each of these places before the player does. Traveling from the Rogue Encampment to the Kurast Docks is traveling across Sanctuary from West to East. The Pandemonium Fortress is located in the Burning Hells, while Harrogath (from the expansion) brings the player back to Sanctuary into the Barbarian region where Baal's army is attacking.

Act	Name of chapter	Town	Final Boss
Act I	The Sightless Eye	Rogue Encampment	Andariel
Act II	The Secret of the Vizjerei	Lut Gholein	Duriel
Act III	The Infernal Gate	Kurast Docks	Mephisto
Act IV	The Harrowing	Pandemonium Fortress	Diablo
Act V	Lord of Destruction	Harrogath	Baal