Videos: Trailers, Teasers, Featurettes
The fourth season of It's Always Sunny in Philadelphia, premiered on FX on September 18, 2008. The season contains 13 episodes and concluded airing on November 20, 2008.
Streaming, rent, or buy It's Always Sunny in Philadelphia – Season 4:
Currently you are able to watch "It's Always Sunny in Philadelphia - Season 4" streaming on Netflix or buy it as download on Apple iTunes, Google Play Movies, Amazon Video, Microsoft Store.