If you think the perfect summer movie involves romance, not robots, then chances are you'll be seeing Monte Carlo instead of Transformers this weekend. The fairy tale-like flick, which takes place in France and then Monte Carlo (duh), features some seriously amazing designer clothes. And the rom-com's three co-stars -- Selena Gomez, Katie Cassidy and Leighton Meester -- have been stepping out all week in chic duds of their own while promoting the film. So who looked the most stylish?

Justin Bieber's girlfriend, Selena Gomez, 18, wore a ruffled purple dress with nude pumps at a press event in New York City.

Katie Cassidy, 24, channeled her Gossip Girl days in a figure-hugging ivory sheath dress with neutral pumps and simple gold jewelry for an appearance on Good Day New York.

PHOTOS: See what Katie wore to this year's MTV Movie awards

Leighton Meester, 25, went for a Carven off-the-shoulder printed dress with a slim belt, a YSL Chyc Cabas tote and strappy Alexandre Birman sandals. In related news, the Gossip Girl star recently snipped blunt bangs and darkened her hair color.

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1,686 Votes
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463 Votes
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602 Votes

Watercooler Poll

Which Star is Most Stylish?

Selena Gomez
Katie Cassidy
Leighton Meester