This paper seeks to present a new understanding of the nature of gang graffiti. Through the analysis of 1522 utterances found on 107 surfaces in the Phoenix, Arizona, metropolitan area, we argue against the commonly held notion that the major function of gang graffiti is to mark territory. A careful consideration of the variety of utterance types, their interactive nature and their location reveals a more complex discourse system reflecting the social structure of the gang subculture. Gang graffiti serves to advertise individual members and gangs, indicate social networks within and between gangs, represent members' views of gang life and honor the dead. While gang graffiti is an antilanguage, often antagonistic in its nature, it functions as cooperative discourse following explicit norms and conventions.