'Cosmopolitan' Celebrates 50 Years With A Very Stylish Birthday Party — PHOTOS

I’m not saying there was an actual email that went out about what to wear to this event, but let’s just say a lot of folks were on the same wavelength when it comes to attire. The Kardashians weren’t the only ones in black at Cosmopolitan ’s birthday celebration, because apparently it was an all-black type of affair. A slew of attendees channeled the magazine’s cover stars and rocked monochromatic looks at the bash.

And I mean, you can never go wrong with an LBD or black pantsuit, so who could blame them? Black was by far the most popular color of the evening, but white was a close second, so Kylie Jenner didn’t miss the mark that much in her light-colored ensemble. Sarah Hyland, Kelly Osborne and more were among the people who wore the night’s trend, so black was clearly the stylish choice if these ladies were on board, too. Next time I have to dress up, there’s no question about what color I’m going to wear. These famous folks have my next outfits sorted.

See nine celebs (besides the Kardashian clan) who owned monochromatic ensembles for the birthday celebration. And Cosmo, let me just tell you — turning 50 never looked so chic!

1. Olivia Culpo

Frederick M. Brown/Getty Images Entertainment/Getty Images

Umm, power suit, much? She looks absolutely amazing.

2. Ruth Kearney

Frederick M. Brown/Getty Images Entertainment/Getty Images

All-black and off the shoulder? She's so on-trend.

3. Stephanie Scott

Frederick M. Brown/Getty Images Entertainment/Getty Images

Look at her working that leg pose and the color of the evening. Get it, girl.

4. Amanda Righetti

Frederick M. Brown/Getty Images Entertainment/Getty Images

I love the mix of sheer and satin in this dress.

5. Sarah Hyland

Frederick M. Brown/Getty Images Entertainment/Getty Images

She works a suit like no other.

6. Briana Venskus

Frazer Harrison/Getty Images Entertainment/Getty Images

You can't go wrong with an LBD/leather jacket combo.

7. Kelly Osborne & Aya Kanai

Frazer Harrison/Getty Images Entertainment/Getty Images

If Osborne and the Cosmo fashion editor both rocked this look, then obviously, this color was the best choice for the evening.

8. Lyndon Smith

Frazer Harrison/Getty Images Entertainment/Getty Images

Simple, yet super classy.

9. Katie Lowes

Frazer Harrison/Getty Images Entertainment/Getty Images

I'm all about this peek-a-boo action happening with this dress.

These ladies killed it in the dress code of the evening.

Want more fearless fashion? Check out the video below, and be sure to subscribe to Bustle’s YouTube page for hacks and tricks!

Bustle on YouTube