Ashlee, Pete & Bronx Party with Lauren Conrad

Little Bronx Wentz knows where the party's at! Ashlee Simpson and Pete Wentz brought their very excited son Bronx to a day party in L.A. on Sunday. And it looks like Bronx may be a bit of a reality TV fan because former Hills cast member Lauren Conrad joined the group as they made their way along with the some other stars into the party!

OK! GALLERY: ASHLEE & PETE SHARE PARENTAL RESPONSIBILITIES OF BRONX

As Ashlee, Pete and baby Bronx made their way to the car to pack things up, Bronx couldn't contain his excitement about going to the party!

OK! GALLERY: PETE WENTZ GETS A STARBUCKS PICK-ME-UP

Mom Ashlee had to separate from her man Pete just for a moment to sign some autographs for fans, but then it was time to get back to the celebrating.

But we bet Bronx was the life of the party!