What has been depicted as persistent, widespread failure of Latino adolescents in schools can be viewed as resistance to the hegemonic pressures of schools, precipitated in part by schools' failure to value and understand their age- and culturally-specific literacies. This paper examines graffiti, one such literacy, as a public literacy practice. Seven samples of Los Angeles area "Cholo" style graffiti are analyzed for their content, nature, and function according to a semiotic model developed in Mexico, in the context of sociohistorical development in East Los Angeles. Results reveal that, contrary to the official school perspective, Chicano adolescents engage in purposeful literate practices that express commonly held values, using culturally recognized forms. These forms are stable across time, but respond in flexible and creative ways when practiced by different users in different contexts. A consideration of the messages that are expressed in Chicano gang graffiti displays evidence of important critiques regarding discourse practices and uses of public space. Implications for educators include understanding the knowledge that students demonstrate as part of these literacies, democratizing the contexts in which students are asked to acquire valued literacy practices, and developing social networks between schools, families, and communities. (Contains 55 references.) (Author/SM)