The theory of language socialization and its subfield academic discourse socialization consider how newcomers are socialized into the practices and identities of communities through interaction with various communicative partners. Drawing on the framework of individual networks of practice, this case study considers the academic writing practices of an English as a foreign language (EFL) learner (Tomomi) at a university in Japan through the lens of her outside-classroom social network. Data were drawn from a study of seven first-year Japanese university students and included interviews, writing assignments with written feedback, and class materials. Through inductive qualitative analysis, shared English academic discourse practices were identified across all participants. For this case study, Tomomi's interview accounts and out-of-class social network were considered in light of these practices to determine her socialization trajectory. Analysis showed Tomomi leveraged many informal social ties to access writing-related support outside the classroom, building knowledge of (and sense of competence in) writing practices. Her interpretations of teacher-written feedback shaped how she evaluated peers as sources of writing support, leading Tomomi to refine her network to individuals who could best support her socialization. The study demonstrates how socialization into academic practices in EFL contexts can also transform out-of-class networks.