Sienna Miller

Sienna Miller. Photos: Nick Harvey, WireImage | Gareth Cattermole, Getty Images

Uptown: The Ralph Lauren Wimbeldon Party
Look: Miller's messy ponytail and bright red lipstick add an interesting contrast to her Victorian lace dress.

Downtown: Twenty8Twelve Collection Launch
Look: Sleek and shiny hair, dewy skin and pale pink lips keep it casual, yet chic.

We're not the only ones obsessed with Sienna's lace & ponytail combo--Geri Hirsch of Because I'm Addicted loves the look, too.