This article reports on the peer socialization of gendered Mandarin practices between three American students and their Chinese roommates in a college dorm in China. Gender is often perceived to be a salient identity category among adult L2 learners overseas. Drawing on the language socialization framework (Ochs and Schieffelin 1984), this study focuses on how gender is constructed and indexed through language as the American students learn to use Mandarin sentence-final particles. Sentence-final particles constitute a unique repertoire to achieve affective work in Mandarin. They have further become a resource among China's urban youth to enact a cute female speech style. In this case study, I employ a qualitative approach with an embedded quantitative component to examine the participants' use of the particles over the course of one semester. The findings show how the American students become socialized into using these particles as gendered linguistic practices in the dorm conversations.