In the field of teaching English as an Additional Language (EAL), digital multimodal composing (DMC) has been increasingly used as a pedagogical approach to support students' writing. While literature highlights DMC has the potential to encourage EAL learners' investment in writing afforded by digital tools, few studies have explored what contextual factors may shape EAL learners' identities in DMC and how they can impact their investment in English writing. This article reports on a qualitative study that investigates the contextual factors that come into play in EAL students' social identity and investment in English writing through DMC in an academic literacy course in China. Through thematic analysis, this study identifies that students' investment in English writing through the DMC project interacted with two major forces in the literacy classroom setting contextualized in the Chinese education system: freedom and constraints. Under such influence, students took on two conflicting identities: free composers and disciplined language learners. Further, I argue that they experienced tensions in these identities. However, the negotiation of the tensions tended to be productive in terms of students’ investment in English writing, which ultimately fostered an enriched understanding of writing.