Summer day parties can be tricky — does the dress code require heels, or will sandals fly [1]? Either way, when we spotted some of Hollywood's biggest stars arriving at Jennifer Klein's Summer soirée [2], our minds immediately went to our own party plans. Would we channel Kerry Washington [3] and dress up in a demure floral look? Or would Elizabeth Olsen's cool cutoffs [4] be our jumping-off point?

Read on for a major dose of warm-weather party wear and get excited for your next get-together. All you'll need to worry about is keeping your margarita nice and icy.

Selena Gomez

In a sexy spin on daytime dressing, Selena opted for a sleek white tank dress that she paired with contrasting black heels and a chic clutch.

Lily Collins

A matching set makes for a playful outfit option, ideal for a breezy picnic or a day by the pool.

Sofia Vergara

While a cotton maxi dress makes for a great casual party option, Sofia proved that, paired with a high-fashion bag and wedge sandals, it can feel dressed up too.

Kerry Washington

Kerry's demure look makes for the ideal garden-party outfit. Pair a floral dress with sophisticated heels and a structured bag to try the look out yourself.

Elizabeth Olsen

If denim cutoffs are your Summer go-to, make them party-appropriate by topping them with a structured top like Elizabeth's long-sleeved style.

Rebel Wilson

Rebel dressed up a graphic tee by pairing it with a knee-length skirt and cat-eye sunglasses.

Leslie Mann

Leslie embraced the season's boho trend in a the ultimate day-to-night party ensemble: a floaty dress paired with lace-up gladiator sandals.