The Truth About Improv On The It's Always Sunny In Philadelphia Set

The long-running FX sitcom "It's Always Sunny in Philadelphia" has dialogue that's unlike anything else on television. It doesn't sound all that scripted, with the characters frequently yelling over one another and all shouting at the same time. It's extremely chaotic but ultimately hilarious, and has led some fans to wonder how much of the series is actually improvised. After all, we know that there are some truly magical moments that were thought up on the spot, like Charlie Day baffling his co-stars with "he doesn't even get us, man" in "The Gang Recycles Their Trash" or Rob McElhenney's character Mac's revelation that he hates women in "Mac and Charlie Write a Movie." But how improv-heavy is "It's Always Sunny," really?

In an interview with Vice where he recounted his favorite episodes, writer and star Glenn Howerton, who plays Dennis, revealed that while there's a lot of improv that goes on during the writing process, the series itself is actually more scripted than some might think. 

One of Howerton's favorite episodes is the two-parter "Mac and Charlie Die," in which Mac and Charlie fake their deaths in order to hide from Mac's recently released felon father, and Howerton explained that when he, McElhenney, and Day write together, they riff and improvise as the various characters. On set, however, they don't aim to improvise much, though he admits that they play pretty fast and loose with exact phrasing:

"It's not really improvising. It's more ad-libbing. I'm going to say the line the way it wants to come out of my mouth in any given moment, and that's the case with all of us. We don't consider ourselves Tennessee Williams — it doesn't need to be word-for-word. Sometimes you improvise and you're like, eh, the scripted line's just better, it's just better. And then there are other times you get on set and you just go and you go and you go and sometimes you go a little further and sometimes you go too far, but the script is just a roadmap. There's always room for improvement."

This style of "ad-libbing" is why the dialogue on "Sunny" sounds so natural coming out of the actor's mouths, and it's likely how we've gotten some of the greatest and most ridiculous line deliveries in the show's long history. Sometimes little accidents can lead to huge moments, like Day's difficulty pronouncing a word becoming the infamous "Pepe Silvia," so it's great that they're not so precious with their scripts that they're not willing to get a little weird with it now and again.

While Howerton isn't keen on calling what the gang does "improv" because they're riffing off of scripted material and not coming up with it off of the top of their heads, he does also note that sometimes a goofy idea on set can turn into much more. "I can't tell you the number of times you get there on the day and somebody will pick up a prop and then somebody makes a comment about it and then next thing you know, the whole scene becomes about the prop," he said. "As long as it pushes the story forward, you just do that version of the scene."

That "yes, and" approach sure sounds like improv, but for them, there's a distinction. It probably doesn't hurt that Howerton, Day, and McElhenney are the show's main writers and are all co-producers in addition to acting, so changing up the scripts on the fly on set is comparatively pretty darn easy. For the most part, they have the ultimate say, so if they decide to flip the script on say, the words "monster" and "Magnum," then who's gonna stop them? As long as they're having fun and making us laugh, the "Sunny" gang should keep doing this style of ad-libbing/improv forever.