LOS ANGELES -- It's probably safe to say that Thursday's episode of "The Office" will feature a television first: No other American comedy series has ever had the Hindu festival of Diwali.

The episode is the brainchild of Mindy Kaling, an Indian-American writer and producer on the series who also plays bubbly Dunder Mifflin employee Kelly. She admits, though, that when it came time to put the celebration down on paper, she had to turn to Google.

"I was a little embarrassed with how little I knew about it," says Kaling, who grew up in Boston. "I'm Hindu, but I'm not really a practicing Hindu, so I had to do a lot of research.

"But it was good too, because I could tell [executive producer Greg Daniels] and people I work with were a little antsy about assigning the Hindu writer the Indian episode. I didn't want to feel like they pigeonholed me, but I felt like I'd done enough episodes" -- she's written four others -- "that it was okay. I was actually a little excited -- I got to learn a little bit more about my culture."

She also got to involve her family. Her parents -- mom Swati a doctor and dad Avu is an architect -- appear in the episode as Kelly's folks, who pepper her boyfriend Ryan (B.J. Novak) with questions about the couple's future. Kaling is proud of the work they did on the episode, but she says the initial experience having them on set was "mortifying."

"Of course I sort of lapsed back into that pre-teen attitude of every single thing my parents do embarrasses me," she says, laughing. "But they were great about it. They were such pros -- they had all these scenes with Steve Carell and they were completely unafraid. They got along effortlessly."

In addition to the Diwali celebration, Thursday's "Office" presses forward with a number of ongoing stories in the show. Michael (Carell) makes a decision about his relationship with sometime girlfriend Carol (Nancy Walls, Carell's real-life wife), Pam (Jenna Fischer) continues her tentative exploration of singlehood and, in the Stamford branch of Dunder Mifflin, Jim (John Krasinski) takes a stumbling step forward in his relationship with new co-worker Karen (Rashida Jones).

"This episode kind of has every single thing I love the most, in anything at all," she says. "It has romance, people getting dressed up in costumes, lots of food, smooching and making out ... and little girls making fun of B.J. Novak."

Kaling devotes a significant chunk of the "Diwali" episode to the Stamford office, which she calls the "Darren Star-type office." She says she and the other writers are enjoying playing the contrasts between the two branches this season.

"For me it's sort of like 'Upstairs, Downstairs,'" Kaling says. "Stamford is like the high-class office. It's only 30 minutes from New York, with good-looking Ed Helms and good-looking Rashida Jones and good-looking Chip [Esten, who plays Jim's new boss]."

That duality may not last too much longer -- the show has an episode called "The Merger" coming up in a couple of weeks, and the episode description NBC provides makes no secret of the fact that the two branches are combining in some way. That could, however, open up a whole new set of possible stories, and for Kelly, fresh avenues of office gossip.

"I love Kelly because she's one of the few people in the office who really loves it," Kaling says. "I think especially in the first season, it was a trial coming to work for everyone. The only reason Jim and Pam came was for each other. Kelly, I think, really loves the office and thinks of it as like this fun, sexy place where she can flirt with her boyfriend and have drama."

Kaling isn't sure, though, whether Kelly and Ryan's already tenuous coupling will last much longer. "I love the way it is now, where she's so unaware" that Ryan is only half-heartedly committed (if that) to their relationship. "You know what it'll be? It'll be her becoming obsessed with someone new. I think that will be it. Right now she's in sort of a blissful other place."