InStyle's 2015 Style 100: The Year in Fashion Hits, Misses, and Hashtags

Everything's coming up daffodils...and marigolds and buttercups. Shades of yellow—like those seen on Jennifer Hudson in Romona, Léa Seydoux in Prada, and Charlize Theron in Dior Haute Couture—made on irresistible bouquet of brights. 

The friendly competition to create the most naked red-carpet spectacle reached new highs (or lows?) at the Met Ball, where even Lady Godiva would have blushed. Beyoncé, in Givenchy Haute Couture by Riccardo Tisci, took it by a bugle bead, followed by Jennifer Lopez in Atelier Versace and Kim Kardashian in Roberto Cavalli by Peter Dundas. 

Imagine the stakes when Kristen Stewart and Julianne Moore were among the guest stars hitting the craps table at the Chanel Haute Couture show in Paris in July. I'll see your Twilight and raise you a Hunger Games. 

Between two YSL biopics and docs about designers (Dior and I is a must), there were enough stylish films to fill a multiplex. Clockwise, from left: Iris, about 94-year-old fashion icon Iris Apfel; The Artist Is Absent, about Martin Margiela; Jeremy Scott: The People's Designer; Saint Laurent; Dior and I; and Yves Saint Laurent. 

Watch your back, Tom Ford. Rodarte sisters Kate and Laura Mulleavy are directing their first feature, Woodshock, starring Kirsten Dunst. 

Rising star Joseph Altuzarra had a breakthrough moment with his prim and perverse fall collection. 

For her first major appearance, at the ESPY Awards, Caitlyn Jenner donned custom Atelier Versace. "It was like every fantasy of my life come true," she said. 

An intentional face-plant was one way to draw attention in a roomful of famous folks, even when they didn't get the joke. 

A sign of the times? Kim Kardashian and Jared Leto went platinum on the same day. 

Has a better ring to it than babylights, right? Olivia Wilde wears this year's fave shade. Is it right for you?

Newly shorn model Ruth Bell rocked the runways with military precision. 

The slimmest and subtlest It bag we've seen in years, Chloé's Drew owes its success to its versatility, its '70s flair, and its appeal to street-style stars everywhere ($1,850; nordstrom.com)

When Alexander Wang bade farewell to Balenciaga after a three-year stint as creative director, his famous friends came along for one last ride in his all-white-and-ivory collection. From left: Suki Waterhouse, Zoë Kravitz, and Nicola Peltz. 

Miuccia Prada's freighted foray into polite macaron pastels proved to be one of the most powerful runway statements of the year. 

The pressure is off. Navigating the advertising scene of the '60s for seven seasons was enough to send Don Draper to a hilltop meditation retreat. Or was it? 

Bikini Day... Argyle Day... Floppy Hat Day... where does it end?

Her Oscars dress was made of 6,000 pearls (faux, as thieves would discover...)

This gown required 27 workers, 987 hours, and 80,000 sequins to make. 

Fashion anniversaries are like birthdays: a cause for celebration. Designers marked milestones by collaborating with friends and reissuing classics. Among them (from left): Betsey Johnson’s golden jubilee of 50 years running was a runway tribute to Blondie, Nicki Minaj, Edie Sedgwick, and her own dance teacher. The best gift Giorgio Armani could give fans for the last 40 years was an update on his styles called the New Normal, and Brazilian jeweler H. Stern introduced galactic designs for its 70th anniversary, playing off the translation of its name ("star" in German). 

The surprise hit of the Gucci reboot was a horse-bit slipper lined with kangaroo fur. Sales are hopping ($995; gucci.com). 

The once-hidden talent chose quirky elegance over flash. 

She brought knowing touches to the ultimate luxury label. 

Their simple approach, with just 15 styles, was a crisp start. 

His femme-noir take on lightness added a winning twist. 

Pinstripes defined their spin on an N.Y.C. landmark. 

At the Oscars, Ford picked up on Witherspoon's signature style for sleek and clean gowns with this icy blue dress, to which he added broad bands of black. It was just a little bit unexpected, and a perfect frame for her natural beauty look for the night.

After three years, Mr. Modern decided to focus on his own label. 

She said she's done with the runways. But for how long?

Her well-received role in Paper Towns, opposite Nat Wolff,was enough to show where Delevingne's heart really lies. 

Studing at a London design school, the Zorro star half-teased he wants to make capes. 

The Lyon-approved collection of designs inspired by the show included gems from Alexis Bittar. Where else would Cookie shop?

Palm Beach color combos aren't just for preppies anymore. The designs were so popular, they promptly sold out.

Olivier Rousteing's admirable embrace of diversity in his model castings finally applied to prices as well. Now we can all dress like the Jenners.

Was there ever a designer better suited to pick the perfect shade of pink? Valli often jokes his second career would be as a florist.

As spare and sophisticated as Christophe Lemaire's previous work for Hermès, this pairing proved that quiet design also has mainstream appeal.

Born on May 2, Princess Charlotte Elizabeth Diana has been described by her father as "a little joy of heaven." She seems unreasonable only in the degree of her adorableness.

Every little monster secretly has the heart of an angel. Lady Gaga's newfound classicism owes to the direction of stylist Brandon Maxwell, but, of course, she couldn't resist the lobster-catching gloves.

Janet Jackson's Unbreakable reminded 21st-century pop stars who's really in control.

The answer to the question "Where Are Ü Now" is, ahem, online looking at pictures of Justin Bieber naked.

Abel Tesfaye went from underground darling to front-row fixture.

Consuelo Castiglioni's circle play gave us reason to actually look forward to thinking about primaries next spring.

The brushed sheepskin coats that opened Nicolas Ghesquière’s fall collection for Louis Vuitton would make a polar bear jealous.

Christian Loubouin's Louboutinize photo-filter app put rose-colored glasses on any picture taken with an iPhone.

Telling the story of Christian Dior in comic-book format was delightful—until he died. The end.

A New York makeup salon from the artists of MAC? Why didn't we think of that? 

Celebrity six-packs never get old, especially those in the category of Who Knew? Thanks are in order to Emporio Armani for uncovering the secret talents of Calvin Harris, and to Tommy Hilfiger for introducing Rafael Nadal to the sport of strip tennis.

In Giorgio Armani Prive.

In Altuzarra.

In Saint Laurent by Heidi Slimane.

Putting a new twist on paparazzi posing, stars introduced twirling to their red-carpet repertoire. Chiffon never had it so good.

In a new commercial for Sauvage Johnny Depp played guitar, took a road trip, encountered a buffalo, buried some jewelry, wore eyeliner, and generally behaved like Johnny Depp.

Art was in the details in the world of Karl Lagerfeld, whose extravagant brasserie set for his fall Chanel collection stayed on point even in a clutch shaped like dinner plates.

Beloved by adolescents, the author penned a novel focused on events from her own childhood.

Atticus, what happened to you? At least you didn’t disillusion us about your power to sell books.