This article explores the uses, effects, and limits of humor for the Guerrilla Girls, an anonymous collective of women artists established in 1985. Using archival materials, oral histories, and contemporary news coverage, it explores how the Guerrilla Girls employed humor to leverage critiques of institutionalized sexism and racism in the art world. It demonstrates how irony in particular helped lampoon art world pretensions, point out inequalities, and render the exclusion of women and people of color absurd. This article asserts the Guerrilla Girls’ place within the history of US feminism and frames the group as belonging to an underexamined history of feminist humor.