It's been hot, hot, hot out the past few weeks, and that means the ladies of Hollywood are showin' some skin!

Sundresses are a cool and comfortable way to beat the heat, so for this week's edition of Style Study, we're taking a look at how some of the hottest celebs have worn the casual, summer look. Check out the different styles and let us know who you think rocked the sundress best!

Reese Witherspoon

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Reese's loose fitting white dress is not only a great summer look, but it's even more perfect for a mom-to-be, totally leaving breathing room for that baby bump. Plus, her straw hat is definitely a great accessory to this summery look!

Ashley Tisdale

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Ashley wears her white-skirted, multi-colored bodice dress as a cover up to a beach party, but she can totally get away with rockin' this look on the street, too.

Jessica Alba

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Jessica's plaid, cotton dress is perfect for a casual day with the family, and can even be sexified by undoing a few buttons to reveal some cleavage!

Jordana Brewster

Jordana's floral look is the epitome of stylish, summer, sundress, but she makes the look even more chic by adding an unbuttoned, denim shirt and giant purse.

Heidi Klum

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Wait a sec, haven't we already seen this look!? Better get shopping for some white dresses and straw hats, ladies, because fashion-expert Heidi is rockin' a very similar outfit to the one we saw on Reese!

Vanessa Hudgens

Vanessa's animal print, hi-low skirted dress is perfect for staying comfy and stylish while heading to meetings, like she did earlier this month. Plus, she totally dresses it up with that giant Chanel purse!

Which lady do you think wore their sundress best?!

Photos Courtesy of: Fame/Flynet