Lauren "Lo" Bosworth, Lauren Conrad's BFF and Audrina Patridge's passive aggressive foe on The Hills, celebrated her 22nd birthday at TAO at The Venetian Hotel and Casino in Las Vegas on Saturday night. Her actual birthday is today (Monday)!

LO AND BEHOLD: A beaming Lauren Bosworth turns 22 today!

We wish Lo nothing but the best. Click to enlarge more Lo pictures below, and check out our famed celebrity birthdays calendar to see what stars are up next!