FLASHBACK: Teenage Jessica Biel Reveals the Joys of Working on '7th Heaven'

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Today marks 20 years since 7th Heaven's first episode and ET was there for every milestone.

"Coming to work is so cool, because everyone is so cool and nice," Jessica Biel told ET on set in August 1996.

WATCH: Beverley Mitchell Celebrates '7th Heaven' 20-Year Anniversary With Adorable Throwback Pics

The actress was just 14 years old when we first talked to her. Co-star Beverley Mitchell was a little older than Biel at 15 years old, despite playing Biel's younger sister on the show.

"I'm an only child, so it's kind of like they're my brothers and sisters," Mitchell said at the time.

Now the married mom of two is in talks to join Dancing With the Stars, according to a source. In the meantime, she's sharing some adorable throwback pics on Instagram from her time of the 7th Heaven set.

After the series premiere, ET returned to the set for the 150th episode in 2003, where Biel told ET she still watched reruns of the show.

"I like it," Biel said. "I just sit there. I'm so cheesy. I sit and smile and weep with it."

WATCH: EXCLUSIVE -- Beverley Mitchell on Justin Timberlake and Jessica Biel's Parenting Skills: 'They Are an Incredible Team'

Today, most of the cast has remained close, and they even showed up to celebrate the opening of Biel's restaurant, Au Fudge, earlier this year in Los Angeles. Mitchell explained that they're so tight, even their children are friends.

"It's amazing that I've got this opportunity to go through this experience with my friends and that our kids are going to be able to grow up together, and that we as mothers can just sit back and talk and chat," she told ET.

When the show completed its 11 seasons, 7th Heaven was the longest-running family drama in TV history, beating out Little House on the Prairie and The Waltons.