Relax during the holidays with five cozy but chic looks

In 2010, Jenna Lyons, the creative director at J.Crew and perpetual style crush among professional cool girls everywhere, started a fashion revolution when she appeared on The Oprah Winfrey Show wearing a casual Breton striped shirt and sequin sweatpants. Three years later, her luxe-but-laidback personal style still has legs, particularly among women pondering holiday party wear.

Of all the (occasionally confusing, sometimes groan-worthy) dress-code descriptors you might see on invitations this season – "glitter & glam," "fashionably festive," "ho ho haute" – those suggesting a more relaxed affair open up your fashion options to a plethora of pieces both elevated and familiar. The co-opting of sequins for day wear has become so accepted in recent years that it's no longer surprising when other fashion codes are subverted. Velvet bedroom slippers worn outside or grey cotton sweatshirts more embellished than wedding dresses suddenly seem appropriate on guests gathered over gingerbread and cups of mulled wine. But this doesn't mean that wearing such pieces isn't tricky: What you have to get right is the successful balancing of casual and chic.

Let's say, for example, that a friend is having an eggnog-and-eclairs party. The safest bet would be a little black dress. But what if, instead, you decided on something cozier: a cashmere sweater that mimics an athletic jumper, say, and corduroys with beaded piping. Accessorize it with an elegant cuff and a pair of pointy pumps and – voilà – you're ready to mingle around the ethanol-fueled fireplace.

Tom Mora, the head of women's design at J.Crew, explains that, by executing pieces in the finest fabrics or finishing them off with restrained ornamentation, the brand's collections remain comfortable but far from slouchy. The retailer's holiday looks include ski sweaters paired with cropped trousers and a sharp pea jacket cut from buffalo-check wool.

"It's clothing that isn't avant-garde in any way," he says from New York. "We're just doing clothes that stand on their own."

What is important, he adds, is that the pieces don't overwhelm the wearer. "You want your clothes to make you shine more, to enhance you," he says. "The best gauge is when someone compliments you not by saying 'That's a great jacket,' but, rather, 'You look fantastic.' "

Of course, J.Crew isn't the only brand with the simultaneous knack for dressing up casual looks and dressing down refined ones. It's what Brunello Cucinelli has been doing for years with his ultra-luxurious Italian label. Ditto Canada's Trish Ewanika, who celebrated her line's 15th anniversary last month.

"To me, it seems like second nature," Ewanika says of her consistent embrace of easy elegance. Her relaxed jumpsuit in crepe georgette, an updated version of an older design, was eagerly welcomed by clients, she notes. It's not hard to see why. Beyond performing double duty at the office and at festive cocktail parties, it is also forgiving enough to accommodate a week's worth of canapés.

Candice Best, who runs a public-relations business and attends her fair share of holiday functions, believes that the fluidity of fashion rules today is a boon for Canadians, especially those who shiver at the thought of wearing a skimpy shift in December.

"You can't talk about fashion at this time of year without referencing climate," the Torontonian says. "I want to be that little bit more comfortable, so, instead of a dress, I might wear heels and sweatpants."

To be sure, her idea of sweats is a relaxed-fit pant in leather or cashmere with elasticized cuffs, not the pyjamas typically sported on Boxing Day. And that is perhaps the most important rule of thumb when it comes to casual evening wear: There is a difference.

Styling by Andrew Sardone. Hair and makeup by Vanessa Jarman for Rimmel London/TRESemmé Hair Care (www.p1m.ca). Prop styling by Stephanie Saunders (www.judyinc.com).