Brace yourself if you're not prepared to feel old, but it's been more than two decades since everyone's favorite pint-sized detective hit the big screen.
The movie was a big milestone for fans of the classic book series, but also because it was the first film put out by the Nickelodeon Movies production company. But - aside from eating lots of mayo and tomato sandwiches - what have the cast been up to in the last 20 years?
Gregory Smith - Sport
Smith played one of Harriet's best friends, but you might know him better for leading roles in Small Soldiers and The Patriot. He also starred in the Disney Channel movie Zenon: Girl of the 21st Century.
As he moved into adulthood, Smith starred in TV's Everwood alongside Chris Pratt. More recently, you might have seen him on Rookie Blue. He's also building up his resume as a director on CW shows like Arrow and Legends of Tomorrow.
Dov Tiefenbach - The Boy with the Purple Socks
Tiefenbach had a handful of small TV roles before landing the mysterious part in this movie, but his career never really took off. He starred in Broadway shows and small movies, but his biggest part since Harriet was playing a drug dealer in Harold and Kumar.
Tiefenbach is also a musician, and was the front man for a "dirty indie pop" band called Theresa's Sound-World.
Charlotte Sullivan - Marion Hawthorne
Marion was a classic "mean girl" before the term was even invented, and Sullivan's performance earned her more parts on shows like Goosebumps, Are You Afraid of the Dark and The New Ghostwriter Mysteries.
After being cast as Marilyn Monroe on The Kennedys, Sullivan has been getting bigger roles on shows like Chicago Fire and Rookie Blue, where she played Gail Peck.
Robert Joy - Mr. Welsch
Joy already had big roles in movies like Waterworld, Radio Days and Desperately Seeking Susan before he played Harriet's dad. He went on to have a number of small parts in horror movies like Land of the Dead and The Hills Have Eyes.
If you recognize Joy from anything recent, it's probably for playing medical examiner Sid Hammerback on CSI: NY. But he still gets all kind of small parts on hit TV shows.