Self-Taught Art, Art Brut, Outsider Art... whatever you call it, one of the largest and most diverse showcase of the stuff is happening this weekend in Chelsea. Once again setting up shop in the Metropolitan Pavilion, the 27th New York edition of the Outsider Art Fair offers a sprawling, sometimes chaotic gathering of 65 exhibitors from 37 cities and seven countries, with the work of hundreds of different artists on display. And maybe it's just because I skipped it last winter, or because eight new galleries have brought their wares to the fair for the first time, but this year's iteration was more surprising and robust than it's felt in a while.

The definition of an outsider artist can be a bit fluid, but the term essentially refers to anyone who makes art without any sort of formal education, without following any particular movement or set of rules, and often without any financial motive, or presumption that their work might be sold. Jean Dubuffet, who coined the term "art brut"—or, Raw Art—said that these are "persons unscathed by artistic culture. [They] derive everything... from their own depths."

But even if there was no intent to profit at the moment of creation, the art here is very much for sale—that's why it's called a "fair" and not an exhibition—at times for prices that are as jaw-dropping (hitting five figures) as anything you'll see at the far flashier Armory Show (which returns in March). Better to not pay attention to the money and focus on the stories of these remarkable artists, many of whom spent their creative lives in isolation, or in institutions. Most of the galleries have brief bios of the artists printed up somewhere in their booths (and many of the people working here are happy to chat with you about them). Occasionally, the artist is in attendance as well.

The Outsider Art Fair held at the Metropolitan Pavilion, 125 West 18th Street between Fifth and Sixth Avenues, and is open today and tomorrow from 11 a.m. to 8 p.m., and on Sunday from 11 until 6 p.m. Tickets are $25.