The current case study explored EFL learners’ engagement with and perceptions of peer feedback over the course of nine weeks. Data were collected from two advanced learners in a TOEFL iBT preparation class in Iran. The sources were triangulated to explore engagement patterns: 1) five argumentative essays, 2) five rounds of interviews, and 3) three rounds of stimulated recalls (SRs). Analysis of data showed that both learners’ perceptions about peer feedback were shaped by prior educational experiences. Analysis showed that both learners came to appreciate the value of peer feedback after providing this feedback, though showing different, nonlinear patterns of engagement. Behaviorally, while one learner gradually incorporated more peer feedback into her writing, the second consistently utilized most of the peer feedback into her revisions and subsequent essays. Affectively, while one learner grew to appreciate peer feedback, the second one reported an appreciation for this feedback throughout the study. Cognitively, one learner started utilizing (meta)cognitive strategies in comprehending feedback, but the second learner always used such strategies. Analysis of the interviews and SRs showed that both learners’ perceptions of and engagement with peer feedback developed over time, though in different ways.