The French label Sézane is known for capturing that elusive Parisian je ne sais quoi—imagine a classic Breton sweater, but with a modern silhouette and a lace collar. To Morgane Sézalory, the brand’s millennial founder, the Sézane sensibility has a depth beyond flippant French chic. “I see Sézane as a committed brand,” she says, referencing its pledge to create sustainably produced collections and a global philanthropic program called Demain, which aims to foster equal opportunities for children, as well as increase access to education and culture.

Artfully arranged goods at Le Grand Appartement, in Paris.

Before there was any brand to commit to anything, Sézalory got her start in fashion by selling her sister’s discarded clothes on eBay. She soon found herself scouring thrift shops across Paris for vintage items, then flipping her finds on the auction site. She would tweak the clothes with her own touch, hemming this and replacing the buttons on that. When her following outgrew eBay, she started her own digital thrift shop, then moved on to the direct-to-consumer retail site Sézane, which features her own designs. Her pieces are well priced and stylish, but not deliberately trendy; the mindset is conscientious, sourcing materials from labels with environmentally friendlier practices. Sézalory embraces the “Buy less, buy better” mantra. On the Web site, high-demand items often sell out—part of Sézalory’s commitment to avoid overproduction by creating limited product runs.

Sézalory embraces the “Buy less, buy better” mantra.

She also has a knack for generating high demand wherever Sézane throws down an anchor, whether that’s in Paris, London, or New York. Sézane’s newest boutique, in Paris, called Le Grand Appartement, is located on the border of the 8th and 17th Arrondissements, and in addition to clothes, it carries shoes, scented candles, pink notepads, and vegan shampoo sticks. Like all of Sézane’s stores, the mood is homey and inviting. Art books such as Warhol’s Polaroids are stacked next to neatly folded blouses. Worn leather couches provide refuge to spouses and kids craned over iPhones. Sugar cookies greet you near the fitting rooms downstairs. At the desk you can pick up an online order, and repair or donate your Sézane garments. A clerk will pour you an espresso from the Marzocco coffee machine. There’s a postage box for sending free postcards and a corkboard for posting handwritten classified ads. It’s closed for the time being, but luckily the e-commerce operation is delivering on schedule.

Caitlin Raux Gunther is a writer based in Paris