"I am very happy," Wolfhard, aka Mike Wheeler, told ABC News. "I guess I knew it was going to happen. I just didn't know when, so it's crazy to think it just got announced and we are going back for a second season. It's surreal."
Since wrapping up season 1 of one of the Netflix series, it's safe to say life's been somewhat different for Wolfhard, 13, and Schnapp, aka Will Byers, 11.
"It was crazy seeing how people reacted to the show," Schnapp said. "There's these big events that we do sometimes like we did today, for instance, there were people holding these Eggo boxes and stuff like that for us to sign."
Wolfhard said he was excited to learn of A-List celebs who were fans of the show.
During filming, Wolfhard and Schnapp came face-to-face with legendary actress Winona Rider.
Both boys said Ryder was a mentor on set.
"I hadn't watched any of her movies, but I knew she was like a big actress and when I met her, I knew she was just really nice because she was always looking out for me," said Schnapp, who played Ryder's son in the show. "I remember when we had to do the scene where she had to do [CPR] ... she gave me gum and she put gum in her mouth and she looked at me and said, 'Now when we do this, our breath won't smell bad.' It made me laugh."
Wolfhard agreed, adding that Ryder was "amazing" to work with.
"She [her character] was an emotional wreck through the entire season, so for her to be off-camera and hang out with us and be funny with us, it's just really cool," he said.
While there's no word on casting for season 2, Wolfhard and Schnapp revealed which of their co-stars they'd like to see make a comeback.
"I'd loved to see Barb back on the show -- even a flashback because Shannon [Purser] is just an amazing actor," Wolfhard said. "I'd love to see her back on set."
Schnapp replied: "I actually don't know if they're going to be in it, but besides seeing Will in the next season, I think it'd be pretty cool to see Eleven come back and what she's like.
"And if the monster is still alive," he added.