We're thrilled to present our favorite Lucky story here on Fab!
Her presence alone was enough to make the teenage-boy attendees swoon, but her skin-baring outfit got our attention, too.
Wearing pieces from Preen's 2011 resort collection, the star showed off some serious cleavage with a square-cut neckline.
Part of why she looked so great was that her top had a bust-enhancing feature built right in: a halter, which helps with lift.
But Lively was able to pull off a racy look tastefully because her ensemble was balanced: She chose to pair the shirt with high-waisted, loose harem pants.
What do you think of her outfit?
For more fashion fun from Lucky, here are more Lucky stories. Related links: Do You Like Scarlett Johansson's New Hair? and 2 Minutes with Celeb Stylist Mary Alice Haney: Get Her Best 4 Tips.