1. Ariana Grande shared this adorable photo of herself eating a cookie as a baby:
2. KJ Apa posted his elementary school photo:
3. The Spice Girls launched their official Instagram with some photos taken on the set of their iconic 1996 debut video, "Wannabe":
4. Adele posted this adorable photo of herself in the late '90s to share her excitement that the Spice Girls were reuniting:
5. Joseph Gordon-Levitt shared this classic photo taken for 10 Things I Hate About You in 1998:
6. Kim Kardashian posted this photo of herself in the 8th grade in 1994:
7. Cher celebrated the 20th anniversary of her CLASSIC single, "Believe," by sharing a clip from the music video for it:
8. Gwen Stefani posted this behind-the-scenes photo taken in 1995, on the set of No Doubt's music video for "Just A Girl":
9. Dan Levy shared this way too cute of pic himself alongside his little sister, Sarah, at her birthday party in the early '90s:
10. Madonna posted this photo of herself and her longtime BFF, Debi Mazar, in the early '80s:
11. Will Smith shared this photo of himself and Celine Dion hanging out backstage at the AMAs in 1991:
12. Nick Jonas posted this photo of himself from the early '00s:
13. Chris Pratt shared this photo of himself in the early '80s, where he looked a bit like Chucky from Child's Play:
14. RuPaul posted this photo of herself serving looks on the streets on New York in 1984:
15. In honor of her 32nd birthday, Lady Gaga shared this photo of herself in 2007, along with a heartwarming message:
Here’s me in 2007 right before I dyed my hair blonde and released Just Dance. It’s now 2018 and I’m so blessed to be turning 32 with a fanbase of Little Monsters I’ve watched spread a message of acceptance and kindness for 10 years now. 💕
16. Mariah Carey posted this photo of herself and Will Smith hanging out together in the early '90s:
17. Ryan Reynolds shared this oh-so-late-'90s photo of himself sporting some pretty Zack Morris looking hair:
18. Emma Watson posted this headshot of herself from the 2000s:
19. In honor of the 25th anniversary of Boy Meets World, Danielle Fishel shared this photo of the cast taken during the filming of the final episode in 2000:
20. Dolly Parton posted the most '80s looking photo of herself and Oprah:
21. Armie Hammer shared his mugshot from 2011, when he was arrested for marijuana possession in Texas:
22. Jennifer Love Hewitt remembered when she and then-boyfriend Carson Daly attended the 1998 VMAs. She also added a sorta shady caption.
23. Nicole Richie shared this cute photo of herself being held by Rashida Jones in the mid-'80s:
24. Halle Berry remembered her role as Miss Stone in 1994's The Flintstones movie:
25. Reese Witherspoon celebrated National Pink Day by posting this screen grab of the queen of pink herself, Elle Woods:
26. Michael B. Jordan shared this sweet photo of himself being held by his older sister, Jamila, in the early '90s:
27. Rashida Jones posted this photo of herself and BFF, Tracee Ellis Ross, in 2000:
28. Julia Roberts shared this photo taken in 1998, on the set of Runaway Bride, alongside her co-star, Richard Gere, and the film's director, the late Garry Marshall:
29. Rob Lowe posted this behind-the-scenes photo of himself with Tom Cruise on the set of their 1983 film, The Outsiders:
30. In honor of her 30th birthday, Rihanna posted a baby photo of herself along with a current day pic:
31. Britney Spears shared this stunning photo of herself taken on the set of her 2001 music video for "I'm a Slave 4 U":
32. Barbra Streisand remembered when she met President Kennedy at the White House Correspondents Dinner in 1963:
33. Janet Jackson celebrated the 25th anniversary of her film Poetic Justice by sharing this promotional photo of herself and her co-star, the late Tupac Shakur:
34. Timbaland took it back to the late '90s, with this awesome photo of himself hanging out with the late Aaliyah, Missy Elliot, and Ginuwine:
Gang Ⅹ Gang Ⅹ Gang. Throwback Thursday. @MissyElliott @Ginuwine #TBT