The Director-based gameplay of the Left 4 Dead games encourages players to enjoy any campaign multiple times. The majority of the official campaigns encompass a larger narrative when played in a particular order, but this is not enforced by the game. On Xbox 360, downloadable campaigns must be purchased (excluding ' The Last Stand' for the first game, which is available for free) and manually downloaded from the Xbox Live Marketplace.

On Steam, downloadable campaigns are added to the games as free updates and are playable simply by purchasing and installing the games. Left 4 Dead initially released with four campaigns, while Left 4 Dead 2 initially released with five campaigns, with both games receiving additional downloadable campaigns after release. The exact process of experiencing a campaign's content depends on the gameplay mode being played, with some modes utilising single chapters of a campaign for each game rather than progressing from one chapter to the next. Chapters are typically played in order, following a narrative in which the Survivors travel from a start point in the midst of the zombie apocalypse to an end point where a rescue vehicle to safety awaits, surviving the onslaught of the Infected as they go. Campaigns are aesthetically presented as if they are individual zombie movies, complete with a poster on the loading screen for each one, and usually consist of several chapters (also referred to as 'levels' or 'maps'). Campaigns (or movies) are grouped sets of environments used for gameplay in Left 4 Dead and Left 4 Dead 2.

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