A dress from MM.LaFleur's  First Addition.

Four years after its women’s workwear site went live, MM.LaFleur has added large-size options to the mix.

The company spent a year researching the category, staffing up with pattern-makers and other specialists with experience in the category and hosting focus groups in its New York office before debuting the clothing that suits women who typically wear sizes 14W to 22W. Eighteen of the e-tailer’s best-selling styles are now part of the MM.LaFleur’s “First Addition” and 20 more items will be added in the weeks ahead. By the end of this year, the company expects large-size sales to account for 10 percent of its overall volume, according to founder and chief executive officer Sarah LaFleur.

She and the senior team approached the expansion as they would with any other category, and made a point of not wanting to identify it as MM.LaFleur Plus. Their interest in the category was prompted partially by a potential deal that didn’t pan out. A while back, executives at MM.LaFleur were approached by another company about developing a plus-size collection on its behalf. During those discussions, they were assured, “don’t worry. It doesn’t have to be under your brand name,” LaFleur said. Aware of how some companies view the category as not so fashionable, LaFleur wanted to change that and make the collection more inclusive. Sizing, for example, is offered in size +1, +2 and +3, and the company’s styling team are available to help customers navigate the sizing.

Creative director Miyako Nakamura, who previously worked at Zac Posen, headed up the development process, hiring technical designer Matilda Ceesay. “We serve professional women and professional women do not end at size 16,” Nakamura said.

MM.LaFleur plans to continue to use consumers’ feedback to build upon the product offerings just as it does with other categories. Shoes and handbags will be added later this year, LaFleur said. This year’s sales are expected to reach $70 million, more than double last year’s tally of $30 million, she said. The company also plans to open another one of its personalized shopping “showroom” concepts in Chicago later this year. After booking what must be at least an hourlong appointment, clients arrive to a curated closet and are helped by a stylist. Purchases are later shipped free of charge. With outposts in New York, Washington, D.C., and Boston, the company is also scouting a second location in New York.