A key element of academic writing involves incorporation of external voices, which is a complex rhetorical and linguistic task. Student writers must face this challenge of using sources to strengthen their own arguments. Appraisal, specifically Engagement, provides a useful framework for analyzing source use in texts, as it considers evaluation and dialogic voicing. This article describes a semi-ethnographic case study that contrasts two undergraduate writers and their writing drafts. Results show similarities and differences based on the linguistic abilities of the students and their experience in writing, but overall improvement in terms of dialogic voicing in the final drafts. Applications to research and instruction for ESL and mainstream writing are discussed.