Fashion in the museum, traditionally a subject of some tension (is fashion art? and so on), has become something of a trend in recent years: Consider the astounding success of the Metropolitan Museum Costume Institute blockbusters — and the attention paid to the opening gala — and assorted ballyhooed smaller shows, like the Isaac Mizrahi exhibition at the Jewish Museum in New York or the Iris van Herpen show at the High Museum in Atlanta. So it probably shouldn’t be a big surprise that MoMA has finally gotten in on the act.

Except that it took 72 years.

Last week, the museum began an extended buildup (and I mean extended) for “Is Fashion Modern?” This megalith, which will try to define the clothes that have defined us, is set to open in December — of 2017.

It will be the first major show MoMA has devoted to dress since 1944, when the architect and designer Bernard Rudofsky curated “Are Clothes Modern?” That was a critical look at the trends of the time that the museum characterized as “in no sense a fashion show,” but rather an attempt to “encourage creative thought about the problems of modern apparel.”

“Well, we are a museum,” said Paola Antonelli, senior curator at the museum’s Department of Architecture and Design and the woman behind the upcoming show. “We always take things slow.”

In the museum’s blog post announcing the exhibition, Ms. Antonelli elaborated a bit. “To say that MoMA has an idiosyncratic history of collecting and exhibiting fashion is a polite exaggeration,” she wrote. “Historically, the museum has deliberately chosen not to engage with fashion in its galleries or its repositories, wary of those most antimodern terms with which it is often derided: ephemeral, seasonal, faddish.”

Ms. Antonelli said the idea for the show had originated with the museum’s director, Glenn D. Lowry, who had noticed her selecting clothing items for the permanent collection such as a white T-shirt, and observed that it was impossible to tell the full story of modern design without taking into account some “very important moments that had to do with fashion.”

Traditionally in museum interpretations, those moments have focused on the kind of items the fashion world likes to consider its version of art: one-off haute couture dresses that take hundreds of hours to make and often achieve the seemingly impossible in cloth. But MoMA’s focus will be on what Ms. Antonelli called “items of fashion that serve as a window onto social, economic and political changes in the world over the last 100 years.”

In other words, think the white T-shirt, Levi 501s, Casio’s digital watch and the little black dress, as well as the kipa and the kaffiyeh. You can argue about whether they qualify as fashion — which is actually part of the point.

The remit of the show “recognized our expertise and lack thereof,” Ms. Antonelli said. “We know a lot about design, but we don’t have a scholarly knowledge of fashion.”

In part, that is why the museum decided to begin talking about the exhibition over a year before its opening. Ms. Antonelli has recruited an advisory board made up of 14 fashion insiders, including Penny Martin of The Gentlewoman magazine and the Hood by Air founder Shayne Oliver. And last week she held a lengthy seminar to begin discussing what kind of objects may qualify for inclusion.

At the moment, she has 350 under consideration; 99 will make it into the exhibition. And though the winnowing and debate can now begin, it all serves to answer one question pretty decisively: Does fashion have a place in the museum?

It’s time everyone stopped being so neurotic about this issue. A critical mass of major institutions seems to agree. The answer is yes.