Based on ethnographic research in a diverse New York City neighborhood, this article examines issues surrounding the practice of crossing from children's perspectives. Crossing refers to the use of language varieties to which one does not have conventional access, practices that could be disparaging or affiliative. The author explores how children distinguished the two types through the principle of authenticity, itself derived by means that went beyond the usual determinants of blood, birth and bodies. While playful, the author argues that crossings were one way for children to participate in the everyday politics of difference and critique the existing racial order. (Contains 7 notes.)