Not long ago, an acquaintance came up to Little House on the Prairie alums Melissa Gilbert and Alison Arngrim as they chatted together at a party. “She says, ‘It’s so good to see you two getting along now,’” recalls Alison. “We didn’t know what she was talking about. It took a while for the light bulb to go on and we realized she was talking about the show.”

It’s easy to understand the confusion if you’re a Little House fan. On the beloved historical drama, which ran for nine seasons, from 1974 to 1983, their characters, Laura Ingalls and Nellie Oleson, hated each other. But in real life, Melissa and Alison have been close friends practically from the day they met on the set. “Alison and I formed an instant bond when we were kids, and she and I text pretty much on the regular,” says Melissa, 59, who has appeared twice on Alison’s podcast, “The Alison Arngrim Show.” Alison, 61, has also joined the conversation at Melissa’s lifestyle site, Modern Prairie.

Alison recalls the first time she met her friend on the set. “She looked small enough that I could put her in my purse, but she also looked like she could chew her way out of it,” shares Alison. “She was this tiny, fierce little thing — all freckles, braids and teeth!” The girls bonded over their lives as longtime child actors from showbiz families. “We started hanging out. We would have slumber parties, would go to each other’s birthday parties and such,” Alison says.

Then as now, Little House fans seemed confused to see the girls together in public. “When we would go to the supermarket to buy treats, people would recognize us and go up to [Melissa] and warn her that I was in the store,” Alison recalls. “They were trying to protect her from me!”

It’s a credit to Melissa and Alison’s acting skills that their clashes looked so real on the show. “We would choreograph our own fight scenes,” Alison says. “When we did the mud fight or any of our rolling-around-on-the-ground scenes, we didn’t have any stunt people. They would just let us loose and we would start swinging on each other like guys in an old western. It would look like we were trying to kill each other, but nobody would get hurt.”

Melissa Gilbert and Alison Arngrim pose together at book signing
Gregg DeGuire/FilmMagic

The instigator in many of these battles was Alison’s Nellie, who was the ultimate prairie mean-girl, but it was Melissa who loved to play pranks on her friends and costars. At one slumber party, Alison woke up to find that Melissa and the other girls had put rocks and pine cones in her bed. “I woke up and threw everything at them as hard as I could,” she recalls with a laugh. “They were terrified of me for two days!” At other times, salt mysteriously found its way onto Alison’s cake, and radishes turned up in her butterscotch pudding! “Radish butterscotch pudding was not half bad,” she adds with a chuckle.

Today, Alison still lives in the L.A. area while Melissa spends most of her time at her property in upstate New York, but the distance hasn’t come between them. The former costars’ shared childhood on Little House has kept them as close as sisters. “We’re still a lot the same,” says Alison. “We got older, but we still laugh at the same terrible things. Melissa’s just a doll and, yeah, we really haven’t changed much at all.”