It's every teenager's dream -- Zac Efron and Jesse McCartney on one roof! ET was there as Zac, Jesse, Vanessa Hudgens, and Rumer Willis partied on the top of the Los Angeles County Museum of Art for the 6th Annual Teen Vogue Young Hollywood Party.

We caught up with Zac, who opened up to ET about his good friend and former co-star Nikki Blonsky and her recent airport incident.

"She's one of my best friends, and it's so unfortunate what happened to Nikki," Zac tells ET.

ET also spoke with Vanessa about the pressure on young actresses to be thin in Hollywood. Watch the young starlet weigh in on the controversy!

Inside the party, the teen sensations were treated to a special live performance by one of this year's break-out bands, MGMT, and viewed the latest spring designs from fashion designer Luella Bartley.

The party was in celebration of the Young Hollywood edition of Teen Vogue magazine.

The issue will profile 19 young actors and actresses on the cusp of stardom as well as some bigger teen stars like the cast of 'High School Musical.'