From the moment Mad Men debuted, the stylised AMC drama about the men and women who work in Madison Avenue advertising in the 1960s has been a tastemaker favourite.
A steady parade of Betty, Peggy and Joan look-alikes have appeared on the catwalks as designers interpreted their favourite looks from the early 60s. But time has marched on in season five, mimicking the fast evolution of fashion during that decade.
Viewers can likely expect skirts to be a little shorter and eyelashes to be thicker when the new season premieres on March 25. Psychedelic colours and patterns could be coming into fashion, too.
The nipped-waist, full-skirt, almost petticoated silhouette that introduced the female characters in season one, set in 1960, would look out of touch with what was happening in the world just a few years later.
After Jackie Kennedy started stepping out in more body-conscious sheath dresses and looser shifts, everyone did. And the collective eye was adjusting to the minis introduced in London by designer Mary Quant that were making their way across the Atlantic when the show left off last season in 1965.
For men, change likely won't be as obvious, but by the mid-60s not every shirt had to be white and not all haircuts were buzzed above the ears. Thank the Beatles and their mop-top haircuts for that.
"The world was changing incredibly fast then," says Scott F. Stoddart, dean of liberal arts at Manhattan's Fashion Institute of Technology.
"It starts in the 60s, and the 70s were just as packed - it was a trajectory. Things slowed down a little in the 80s, which were actually more conservative, more like the 50s when the whole decade looked the same."
Culturally, beatniks were becoming mods, rock'n'roll was taking hold, and the move from stockings to pantyhose - and eventual bra-burning - all influenced mid-60s fashion.
It will all probably mean a lot to upwardly mobile Peggy Olson, who started off wearing matronly clothes when she was Don Draper's secretary but is a feminist at heart, says Stoddart, who wrote Analyzing Mad Men: Critical Essays on the Television Series.
He's most interested in the fashion evolution of Draper's daughter, Sally, who will be in middle school in suburbia, which eventually becomes a hub of change with girls wearing overalls.
Sally, he says, is "a rebel in the making".
That was the norm for adolescents and teens, who adopted Lyndon Johnson's daughters as their style role models in a way that Jackie Kennedy had been for their mothers.
"They were hipper," Stoddart explains.
"They were parting their hair in the middle."
Don Draper probably won't like that one bit on Sally, Stoddart observes, because for all his smoking, drinking and womanising, he's more conservative than one would think. He notes an earlier episode in the series where Don wasn't pleased at all to see then-wife Betty in a bikini.
"If you look at the whole decade, from 1960 to 1970, you still have some people who weren't changing, but the younger people were pushing fashion in a totally different direction," agrees Janie Bryant, the show's costume designer.
The character is essential to the costume, Bryant says. The retro moment largely credited to Mad Men - and bringing back styles she personally loves - is icing on the cake.
"It's amazing to me how the fashion has been this huge explosion," she says.
"I'm telling the story of the characters through the clothes, but it's not about a 'fashion show', and I think that's why people are so excited."
Peggy, who works her way up to her own office at the ad agency, is definitely someone to watch, Bryant says, because she understands that her wardrobe is an expression of herself.
The others also express themselves through their clothes, but don't always realise it, she says.
"Betty Draper Francis - her roots are growing up in the 1950s, so she's always a little bit updated 50s, and that says a lot," Bryant says.
"She cares about appearances more than she does fashion. She likes the appearance of perfection."
Joan, who always liked the tighter cut anyway, could start showing an appreciation for the richer, more luxurious fabrics that were becoming popular.
The polish that comes with the Mad Men look resonates with consumers right now, says Banana Republic creative director Simon Kneen, who has collaborated with Bryant on Mad Men-themed collections. The second batch of styles is in stores now.
While you might not do the matching bag and shoe that Betty wears, the chicest women of today will certainly pay attention to choosing a complementary bag or shoe.
"It's not about being eclectic right now," he says.
What was nice about women in the workplace then, and it's similar right now, is that they weren't trying to be men, Kneen says. Even as women in pantsuits take hold in the later 60s, it wasn't in an oversized manly shape, although that would become more popular years later.
Men's office attire was fairly consistent through the 60s, although they broke out some coloured shirts, FIT's Stoddart says.
For them, the bigger change was the "silly wide tie" that came in the 70s. Still, he says, some of the ad world's younger executives might start wearing high-collar Nehru jackets and there will be more sideburns and beards. "You will see flickers of change," he predicts.
Elizabeth Taylor dictated many beauty trends of the 60s. As she switched from red lips and flawless skin to dramatic eyes and pearlised, pale-pink lips, so did most women, says celebrity makeup artist Agostina.
Models Twiggy and Jean Shrimpton further modernised (actually mod-ised) Taylor's Cleopatra look for everyday and women bought easy-to-use makeup kits that told them how to do everything.
"Models then became the idols. Everyone wanted to look like these models," Agostina says.
"They were the rebels for a little while, and really set the tone. They had a great impact in a short amount of time."
It's a "double-edged nostalgia" that's bringing it all back, says Stoddart.
"It's people who remember, 'Oh, when I was young - I wish we could go back to that simpler time', and then it's with the younger generation - at FIT, Mad Men is very popular with students. I wondered why, but it's a very naughty era, and that's what they like.
"It's things they can't do."