"Mean Streets" focuses on the streets, parks, schools, and commercial venues of Chicago from the era of the 1919 race riot to the civil rights battles of the 1960s to cast a new light on street gangs and to place youths at the center of the twentieth-century American experience. Andrew J. Diamond breaks new ground by showing that teens and young adults stood at the vanguard of grassroots mobilizations in working-class Chicago, playing key roles in the formation of racial identities as they defended neighborhood boundaries. Drawing from a wide range of sources to capture the experiences of young Mexicans, Puerto Ricans, African Americans, Italians, Poles, and others in the multiracial city, Diamond argues that Chicago youths gained a sense of themselves in opposition to others.