In May 2021, Ashley stepped out in a pair of black leather slides, a longline trench coat, and dark flared trousers. Her look was yet another almost black monochrome moment save for her oversized cerulean blouse.

Ashley went for an all-black look consisting of a dark button-up, silk skirt, and leather jacket tied around her waist. She relied on her maroon wide-brimmed hat for a pop of color.

The duo stuck to their signature black color palette at the Youth America Grand Prix's 20th Anniversary Gala in New York City. Mary-Kate contrasted her sleek coat and croc bag with a pair of red Manolo Blahnik kitten heels.

The Olsens donned head-to-toe leather for the 2019 Met Gala's "Camp: Notes on Fashion," putting an edgier spin on their classic style with leather gowns from Chanel.

Ashley walked the carpet at the Vanity Fair Oscars after-party in a floor-length belted black dress that she accessorized with strappy heeled sandals and a small envelope clutch.

The sisters embraced their love for flowing dresses at the 2018 Met Gala in dresses that combined their past and present senses of style. Ashley sported a colorful metallic gown by Paco Rabanne while Mary-Kate wore a gown by the Olsens' own line, The Row, over a Paco Rabanne tunic.

Mary-Kate and Ashley proved their penchant for classic style at the 2018 CFDA Fashion Awards — where they won the award for Accessories Designers of the Year — wearing structured jackets and skirts. And of course, they finished off their look with top-notch accessories.

At the 2017 Met Gala, which highlighted Japanese designer Rei Kawakubo, the Olsens returned to their boho roots and wore lace dresses, which were accompanied by pops of color in the form of beads and fur.

The Olsens attended the 2017 CFDA Fashion Awards in outfits featuring qualities they maintain in their designs for The Row: timeless silhouettes, crisp tailoring, and neutral tones.

For their appearance at the 2016 Met Gala, which had the theme “Manus x Machina: Fashion In An Age Of Technology,” the designer duo stayed true to their personal style in sleek, neutral-hued floor-length dresses.

At the 2015 CFDA Fashion Awards — where the Olsens received another award for Womenswear Designers of the Year — the sisters each wore black silk ensembles, accessorizing with black clutches and white diamond jewelry.

In September 2015, the duo was spotted outside of their SoHo office. Mary-Kate's wide-leg pants and simple sweater were worn with flip-flops and layered necklaces. Ashley chose skinny jeans and a button-down, which she finished with taupe flats.

In 2015, the Olsen twins attended the event titled “China: Through the Looking Glass” while wearing coordinated vintage Dior by John Galliano gowns.

Arriving at LAX, the sisters showed off their polished yet cozy airport style. Mary-Kate wore a brocade coat, which she styled with black criss-cross slides and an oversized scarf. Ashley threw a gray pashmina over her shoulders, wore croc loafers, and carried an oversized black bag.

In 2014, Met Gala honored designer Charles James, who was known for his ballgowns. The Olsens paid homage to the designer with vintage gowns from Chanel and Gianfranco Ferré.

In April 2013, Ashley strolled around NYC in her signature black-on-black combination, this time with an added pop of color thanks to a blue croc bag slung over her shoulder.

In 2013, Ashley got creative with the Met Gala's “PUNK: Chaos to Couture” theme by choosing a floaty vintage Dior dress for the occasion.

For the 2013 Met Gala theme, “PUNK: Chaos to Couture,” Mary-Kate dipped into her extensive vintage collection. She wore a drop-waist dress by Chanel, which she styled with an embroidered silk robe layered on top. She finished off with bohemian accessories, including layered necklaces and crystal earrings.

In 2012, Mary-Kate attended the Met Gala solo. For the year's “Schiaparelli and Prada: Impossible Conversations” theme, she chose a black draped gown from The Row and a metal clutch.

Ashley touched down in Los Angeles wearing an ensemble true to her classic style. She layered a cozy brown coat over black skinny jeans and finished off with two-tone flats.

The Olsens received the Womenswear Designers of the Year Award at the 2012 CFDA Awards for their minimalist fashion brand, The Row. Both sisters wore sleek dresses and carried classic handbags to the ceremony.

For 2011's Met Gala theme titled “Alexander McQueen: Savage Beauty,” Mary-Kate chose a sweeping red Givenchy gown.

Ashley chose a monochromatic look for the evening, wearing a black Dior gown with billowing white sleeves.

Ashley exited a car at Lincoln center in a texture black dress and pumps. She wrapped herself in an ink green furry stole for a pop of color.

For 2009's Met Gala, which was themed “The Model As Muse,” Ashley attended with then boyfriend Justin Bartha. She chose a white gown from her label The Row complete with long sleeves and an open back.

Mary-Kate opted for a vintage look on the red carpet, donning a silver and tiered gown by Christian Lacroix.

The duo sat front row at Chanel's 2008 fashion show, both wearing YSL's signature oversized sunglasses. Mary-Kate opted for leather leggings, a gray sweater, and tan platform sandals. Ashley chose a white Chanel coat with black tights and booties.

At the 2008 Met Gala, which was themed “Superheroes: Fashion and Fantasy,” the pair took on sleek silhouettes. Both sisters wore gowns by Diane von Furstenberg and heels by Christian Louboutin (who accompanied them for the evening).

Ashley and Mary-Kate sat front row at the Dior fashion show in Paris. Mary-Kate chose a black ball gown, which she contrasted with a red knit beret. Ashley chose a furry white coat, black tights, and black heels.

The 2007 Met Gala theme was “Poiret: King of Fashion” — an ode to French designer Paul Poiret. Ashley chose a Grecian white column gown, which she belted with a thick patent waist belt.

This dramatic gown, a design from Lily Et Cie by Rita Warnick, was a dramatic choice by Mary-Kate for the 2007 Met Gala.

Ashley and Mary-Kate channeled old Hollywood glamour at a party at LA's iconic Chateau Marmont. Though both wore a bold red lip, Ashley kept the rest of her look neutral while Mary-Kate chose an emerald gown.

In October 2006, Mary-Kate entered the Ritz Hotel in Paris dressed in a punk outfit that included knee-high leather boots and an Alexander McQueen skull print scarf.

For the Anglomania-themed event, Mary-Kate chose a black dress with lace sleeves by Badgley Mischka. Ashley also wore the designer to the event. "These were custom looks, so we went through fabrics together and they gave us an idea of what they liked," designers Mark Badgley and James Mischka told Page Six in 2018. "This was around the time that they were always photographed running around with their Starbucks, so it was fun to glam them up."

For the 2006 CFDA Awards in New York City, both Ashley and Mary-Kate chose colorful floor-length gowns.

For this 2005 amfAR gala at the Le Moulins de Mougins in France, the twins went back to wearing bohemian-inspired ensembles with long, flowing (and in the case of Mary-Kate, tiered) dresses.

For 2005's “The House Of Chanel” Met Gala, the sisters got creative. Mary-Kate continued to channel her bohemian style with a floor-length vintage white cotton dress and layered jewelry. Ashley chose a gold high-low dress from Oscar de la Renta.

In September 2014, the duo attended Marc Jacobs' fashion show in New York City. Ashley chose a more classic look consisting of blue jeans and a white button-down. Meanwhile, Mary-Kate went for an outfit with an unexpected color combo: pink and green.

To receive the honor of having a star on Hollywood's iconic Walk of Fame, Mary-Kate and Ashley went for more classic ensembles. However, both outfits carried free-spirited notes that were reminiscent of their go-to boho style.

For a night out in New York at the Tribeca Film Festival's Vanity Fair party, the sisters chose polished yet playful ensembles. Ashley chose a polka dot top with wide-leg pants, accessorizing with an orange clutch and green pumps. Mary-Kate kept to a black and pink theme.

The duo walked the red carpet at the Tribeca Film Festival in New York City while wearing coordinated brown outfits.

The sisters walked the orange carpet for Nickelodeon's 2004 Kids’ Choice Awards in looks that while all their own, still managed to be coordinated. Mary-Kate accessorized a deep blue dress with oversized turquoise earrings, jelly bracelets, and gold gladiator sandals. Ashley went for a more streamlined look with a striped halter, brown silky trousers, and gold strappy heels.

At the opening of Fox Sports Grill in Irvine, CA the sisters opted for coordinated looks that included baby doll tops, flared jeans, and ballerina-style flats. Mary-Kate layered up the look by adding a blazer, scarf, and printed hat.

The Charlie’s Angels: Full Throttle premiere is where the two sisters showed their love for the bohemian style. Ashley wore a tropical-inspired floral print dress while Mary-Kate donned a flowing kaftan dress.

The Olsens embraced the trend of low-rise bottoms for the album release party celebrating NSYNC's "Celebrity" in 2001.

Mary-Kate and Ashley wore coordinated ensembles for a similar-but-different look to the Anna and the King premiere in 2000. The pair sported fitted cardigans with slip skirts and strappy sandals, an outfit that's still on-trend today.

The twins went for a red and blue, almost twinning moment in their coordinating slip dresses with floral prints, lace panels, and velvet swatches. Plus, the pair wore chunky heels that would fit right in with 2021’s platform shoes trend.

The sisters wore coordinated looks to the premiere of Spice World in 1998. The shiny blazers and piece-y updos were peak '90s style.

For their premiere of It Takes Two, the Olsens wore coordinated skirt sets with Mary-Janes.

At the 12th annual VSDA convention in 1991, the young stars made an appearance in matching outfits featuring denim overall dresses, red button-down tank tops, and bandanas as hair accessories.