It's impossible to find 10 things to hate about this awesome throwback post.
The 44-year-old actress posted a picture with her co-stars Julia Stiles, Joseph Gordon-Levitt, Andrew Keegan, David Krumholtz, Larisa Oleynik, and the late Heath Ledger.
"Just a bunch of kids having the time of our lives up in Tacoma/Seattle," Union said in the post. "First movie and an experience that I'll never forget."
Union continued to praise her friends in the post, calling them "The best/coolest/most generous group of people to share my 1st film experience."
She ended the caption by paying tribute to Ledger, who died of an accidental drug overdose at the age of 28 in January 2008.
"❤ and eternal light #RIPHeath"
Despite being almost 20 years old, 10 Things I Hate About You is still praised by fans and critics alike. The film is also responsible for launching the careers of many cast members, including Ledger, Union, and Stiles.