The two sitcoms could hardly be more tonally different, but this week’s crossover episode of “Abbott” was relatively seamless.

Philly pride runs strong, even for celebrities. The Welcome to Wrexham creator and Bradley Cooper are not the only famous guest stars to pay tribute to their roots in an episode of Abbott. Eagles football players Jalen Hurts and Jason Kelce also made cameos in Season 3, as Abbott ’s always one to cater to their PA fanbase.

The collaboration commences with Season 4, Episode 9, of "Abbott Elementary," airing Jan. 8, and will continue with a follow-up episode of "It's Always Sunny in Philadelphia," expected to air in the show's upcoming Season 17.

"Abbott Elementary" star Janelle James is schooling us on that "It's Always Sunny" crossover and unwinding with the help of "rich people" wellness.

After much anticipation, the unlikely meeting of the two worlds unfolded on Wednesday's installment of "Abbott Elementary."

This week's "Abbott Elementary" episode is just half of the story. "Volunteers" featured the long-awaited crossover with FX's long-running "It's Always Sunny in Philadelphia," as told from the vantage point of the hit ABC sitcom.

On Wednesday, you have not one, but two hilarious reasons to turn on your TV, as the casts of It's Always Sunny in Philadelphia and Abbott Elementary will deliver their highly anticipated first crossover episode.

It might be always sunny in Philadelphia, but that doesn't mean there aren't some clouds about to hit Abbott Elementary school. A major crossover event kicks off on Wednesday's episode of Abbott Elementary,