Selena Gomez [1] took it back to the '90s in honor of pal Julia Michaels's 26th birthday. On Sunday, the 27-year-old singer attended Julia's prom-themed party, and it looked straight out of a movie. Selena wore a black slip dress with a matching choker and boots, while Julia rocked a red babydoll dress and gloves. "My love, my heart and my soul @juliamichaels," Selena captioned an Instagram photo of her and Julia [2]. Julia's actual birthday is on Nov. 13, and from the looks of it, the party was a hit.

Selena and Julia have been friends for quite a few years now. In fact, Julia has written a lot of Selena's famous hits [3], including "Bad Liar" and "Slow Down." In a heartfelt Instagram post back in January, Selena opened up about her friendship with the songwriter [4], calling Julia her "sweet soul sister." "Julia you have been a huge part of my life," she wrote. "You have taught me how to have courage when I have self doubt." See photos from Julia's birthday extravaganza ahead!