Kristen Bell

Celebs were out in full force on Sunday night at this year’s Do Something Awards, which honors young people’s efforts to help causes they care about. Our friends at Give Back Hollywood were also in attendance and caught up with some of our favorite charitable celebs like Victoria Justice, Kristen Bell and Mario Lopez as they hit the star-studded red carpet.

Actress/Musician Demi Lovato and TV Personality Kim Kardashian arrive at the 2011 VH1 Do Something Awards at the Hollywood Palladium on August 14, 2011 in Hollywood, California. View entire gallery here

When you've got a face and body like Olivia Wilde's you can generally do no fashion wrong. But the "Cowboys and Aliens" star came pretty darn close last night, donning a long pleated Chloe dress to VH1's Do Something Awards in Hollywood. The 27-year-old accepted the Do Something Movie Star award for her socially-conscious ways, beating out Kristen Bell, Orlando Bloom, Kathy Griffin, Scarlett Johansson and Daniel Radcliffe.

While the 2011 Do Something! Awards don’t air on VH1 until August 18, Demi Lovato, Justin Bieber, Kim Kardashian, Sophia Bush, Mario Lopez, Kristen Bell, host Jane Lynch and many more stars walked the red carpet for tonight’s ceremony. The event honors young people’s commitment to social change. Lovato will perform during the telecast, and presenters including Olivia Munn and Nick Cannon will be part of the festivities, too.

They joked last year that they were girlfriend and boyfriend before despite the 13 year age gap - and Justin Bieber and Kim Kardashian were reunited last night. However, in a neat twist, it now appears that the pair are in the business of matchmaking for other people. Kim, 30, and Justin, 17, were back together at the Do Something Awards last night and were pictured having fun together.

Brittany Snow arrives at the Do Something Awards on Sunday, Aug. 14, 2011, in Los Angeles. The awards recognize young people who have a positive impact on their communities. View more pictures from the 2011 Do Something Awards here!

We’ve already told you about the all-star lineup of presenters and performers who will be at the 2011 Do Something! Awards this year, a list that includes Adam Lambert, Victoria Justice, and Nick Cannon, to name a few. But just today we learned of a few more A-listers who will be on hand at the show and if we can be quite honest, this list? It’s insane. Check out the full roster of attendees and presenters after the jump! The Do Something! Awards air on Thursday, August 18 at 9 p.m. ET/PT.

In the work of spreading humane values throughout our society and our culture, The HSUS gets a lot of welcome help from taste-makers in the art and entertainment industry. We’re lucky to have two celebrity friends of The HSUS nominated this year for prestigious Do Something Awards from VH1 and DoSomething.org. Please vote for Nigel here.

Vegan actress/model Olivia Wilde and vegetarian star Kristen Bell have been nominated within the same category for this year’s Do Something Awards—the awards given to the “do-ers” in their field, cause or issue. The two plant-based-diet-fueled beauties are facing off against fellow Hollywood performers Orlando Bloom, Daniel Radcliffe, Scarlett Johansson and Josh Duhamel in the Do Something movie star grouping.