The Sin City actress was spotted running errands in Los Angeles earlier in the day, looking oh-so-cool in an oversized blazer.
She slipped her pins into blue wash skinnies, adding heeled ankle boots and a crisp white shirt.
The starlet gave her neutral ensemble a pop of colour with a cherry red bag adorned with stand-out gold spikes.
Despite sporting bedhead tresses, Jess still looked positively stunning with minimal make-up and retro sunnies.
But come nightfall the actress really amped up the glam as she stepped out at the Who What Wear and Cadillac 50 Most Fashionable Women Of 2013 event.
Jessica sizzled in a long-sleeve white frock designed by Wes Gordon, which featured two box pleats and striped inserts.
She added nude pointed courts with silver toecaps and toted a textured black clutch.
Her tresses were styled in loose waves and she skipped the eyeshadow, opting for mega-fluttery lashes and a vampy pout.
Loving your style, Jess!
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