The gang heads to Abbott Elementary.

The ABC series will crossover with FX's It's Always Sunny in Philadelphia for Season 4. Rob McElhenney, Danny Devito and Charlie Day will appear in the episode, as confirmed by a photo posted to social media on Thursday.

The Sunny cast members are pictured alongside Abbott star and creator Quinta Brunson, as well as Tyler James Williams and William Stanford Davis. It's unclear who else the Paddy's Pub crew will be battling it out with in the episode.

photo.twitter.com/ymQTnjNE6i