The tradition of Memorial Day has become barbecues and pool parties, and for celebrities it's no different! Tons of stars came together on Monday in Malibu, California to celebrate the holiday at Hollywood producer Joel Silver's annual Memorial Day party.

It was a crowd of mixed ages, with celebrities like Selena Gomez, Ashley Greene, Kate Beckinsale and Gwen Stefani with her family in attendance. Of course, there were fun games and beach time involved -- and we've got some hot pics of celebs mingling at the event. Click through the gallery to check 'em out!

Ashley Greene and Selena Gomez at Joel Silver's Memorial Day Party

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One cool thing about an outdoor, daylong event is that we get to see celebrities in much more casual, laidback, street clothing rather than their usual fancy attire at big events. Ashley rocked a hot springtime trend -- the maxi dress -- in red (so patriotic!) and a pair of wedges. Meanwhile, Selena wore a simple, gray dress with a smiley face, with her hair pulled back and flat sandals.

Click through the gallery to see who else was in attendance and get an idea of what you can wear to your upcoming summer bashes!

What are your favorite barbecue styles?!

Photos Courtesy of: Fame/Flynet