A mid-semester peer assessment (PA) was implemented in two iterations of a large undergraduate psychology module (n = 102 and 107 students respectively). Students completed a written assignment, evaluated the work of a peer (providing a grade alongside rubric-assisted and open-ended written feedback), and revised their own work based on the feedback they received. Half engaged in the process anonymously. A subset of students across both cohorts completed pre- and post- questionnaires measuring beliefs about PA and emotional states. Changes in these variables after participating in the PA were measured, and the impact of anonymity was investigated. Feedback quality was also analysed using an adapted coding scheme. Students’ social concerns about PA decreased after participating, and anonymity did not impact on their experience of the process. Feedback quality was low. The instructors’ reflections on the process and implications for practice are discussed, placing particular emphasis on the large class context.