The Guerrilla Girls, an anonymous group of female artists and art-world professionals, first affixed iconoclastic posters to Soho and East Village walls in 1985, provoked by an international survey of painting and sculpture at the Museum of Modern Art. The New York show unwittingly confirmed what the group knew to be true, that insufficient notice was being paid to female artists. Of the 169 artists whose works were included in the survey, only 13 were women. Thus began a campaign—waged largely with cold, hard facts and a humorous twist—to raise the consciousness of the art world.

Four years later the group turned their attention to the permanent collection of the Metropolitan Museum of Art. The result was their most celebrated poster, Do women have to be naked to get into the Met. Museum? Surveying the works on display in the museum's nineteenth- and twentieth-century galleries, they tallied the number of female nudes versus the number of male nudes and counted the number of works by female artists versus the number by male artists. Their findings were startling: not even 5 percent of the artists represented in the modern galleries were women, while fully 85 percent of the nudes in those same galleries were female. The image they made to expose this discrepancy features a reproduction of the sumptuous nude in Jean-Auguste-Dominique Ingres' La Grande Odalisque, with her face hidden by a gorilla mask, the Guerrilla Girls' signature disguise. When presented to the Public Art Fund of New York City, which had commissioned the design for a billboard, the work was rejected. The Guerrilla Girls, in retaliation, rented advertising space on New York City's public buses, where the poster's display caused a stir.

The Guerrilla Girls guard their anonymity. In the role of "feminist masked avengers," their stated mission is to use "facts, humor, and outrageous visuals [to expose] sexism, racism, and corruption in politics, art, film, and pop culture." Since the mid-1980s they have aimed their sassy wit at museums (including the National Gallery of Art), art dealers, curators, collectors, critics, and even other artists.

In 2007 twenty-one staff members of the National Gallery of Art, calling themselves the Gallery Girls, made personal contributions to an acquisition fund in order to purchase for the Gallery the Guerrilla Girls' Most Wanted portfolio—a portfolio containing thirty of the group's most illustrious posters from 1985 to 2006, including the now historic 1989 poster about the Metropolitan Museum of Art.