What Exactly Constitutes "Cocktail Attire?"

Yes. Not only did fashion "It" girl Alexa Chung follow the short-dress rule, but she defined it with her own style. Instead of wearing a garment that was extra tight or sultry, she went for a feminine piece with decorative florals and a quaint little bow. The metallic material and cage heels, gave the outfit its party ready stamp.

Yes. When I think of cocktail party–appropriate pantsuits, I immediately picture a sleek and clean blazer with matching trousers. Enter Kourtney Kardashian with her plunging neckline. The oversize fit and tapered pants are sexy without exposing too much. (Though, if you're going to a party that is a little more conservative, you might opt to wear a silk camisole underneath your blazer.) Accessorize with a pair of heels and you're ready to party.

Yes. Yara Shahidi masters the quintessential cocktail attire look: the little black dress. The LBD works especially well for company parties or your friend's last-minute birthday celebration. Make your dress stand out with a statement shoe. Shahidi chose a cutout stud embellished heel, but you can go for something feathered or colorful, like this Sam Edelman red pump.

Yes. You'll find most women choose neutral or dark colors since they're easy to wear, but give brighter garments a try. I recommend using Emma Roberts' Vanity Fair outfit as inspiration. The cap sleeve red minidress is eye-catching and bold. Her shoes match the dress perfectly. And, a red lip seals the deal. Roberts' party attire is proof red on red on red is a powerful ensemble.

Now, you're ready to shop...

Dress the Population mermaid dress, $216

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When that wedding invite comes in the mail, "cocktail attire" emblazoned across it, grab this dress. The halter neck highlights your shoulders and back while the mermaid silhouette brings out your curves. Style with beige pumps or metallic rose-colored sandals.

Calvin Klein double-breasted blazer, $1,900

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Calvin Klein straight-leg pants, $890

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Rather than reach straight for the standard black-blazer-and-pants combo, broaden your style range with this checked wool two-piece. The maroon hue is muted, but still interesting, while a yellow stripe down each pants leg adds a nice contrasting color. Since the buttons do snap all the way up, you can technically rock the blazer shirtless, for a sexy secret only you know. Wear with a simple heel like these Pauwau sandals.

No. 21 sheer lace top, $240

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This lace tank qualifies as a party top because 1) it has an evening-wear vibe and 2) it looks luxurious. Made in Italy, the tank is constructed with thick beige velvet straps and a tulle outer layer, giving it a semi-sheer appearance. You can wear this underneath a blazer or with a shimmery skirt for a winning combo at any party.

Ted Baker London sheath dress, $315

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This Ted Baker dress is elevated and sophisticated thanks to the tailored cut, while cleverly placed florals give the dress a ladylike vibe. This is the type of dress you can wear to Very Important work drinks with a blazer, or to your friend's bridal shower luncheon on the weekend.

Milly black skirt, $425

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Once you have this black skirt, the top half of your look will easily come together. Style this with the sheer lace shirt, above, or any silky camisoles you own. The ruche details and ruffle hemline (my favorite aspects) give the skirt a unique flare and are quite pleasing to the eye. Wear with your favorite pair of heels.

Chelsea28 lace sheath dress, $149

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Move aside LBD. This lace and chiffon ruffle minidress is my new go-to for upcoming holiday parties. The pattern is intricate but wearable, while the velvety band highlights the narrowest part of my waist. I'll wear this dress with small pearl stud earrings and classic black heels.