“Ours, Not Theirs,” this text by the Chicano artist and poet Carlos Cortez about Diego Rivera, appeared in the Industrial Worker in May of 1986. Writing under the pseudonym Koyokuikatl, Cortez comments on an exhibition at the Detroit Institute of Art celebrating the centennial of the birth of Mexican muralist Rivera, one of the so-called “tres grandes.” Although he considers the contested relationship Rivera had with the Communist party during his lifetime, Cortez nonetheless argues that Rivera’s art is revolutionary due to its critique of capitalism and its compassionate portrayal of the poor and working classes. A central figure in the Chicago art community during the second half of the twentieth century, Carlos Cortez (1923–2005) was an artist, cartoonist, printmaker, photographer, poet, and political activist. Born in Milwaukee, Wisconsin, Cortez’s father was an organizer for the industrial Workers of the World and his mother, who was German, was a socialist and a pacifist. Cortez spent his life in the Midwest, moving to Chicago in 1965. His graphic art addresses Chicano, Latino, and Native American issues; Mexican-American and Latino identity and culture; and workers' rights. This article addresses the theme Art, Activism, and Social Change because it offers an assessment of Rivera’s Detroit mural cycle that focused on aspects of social justice and the political context that fostered the murals.