This article investigates the identity construction process of China's rural-urban migrant children through analyses of their discourses and of their use of language. Rural children have relocated to the urban centers with their parents on a massive scale over the past decades as China has undergone rapid economic changes. Many migrant children are able to attend urban public schools, and their identity construction emerges as an important issue that attracts increasing public and scholarly attention. This study draws on ethnographic data and presents four examples to illustrate the complex process of migrant identity construction. The results show that the migrant children deploy a range of linguistic features and claim multiple identities; in order for their identities to be established in social reality, they have to go through negotiation processes in which their identities are evaluated, ratified, challenged, or denied. Language is at the center of such processes.