This study investigates how an instructional intervention focused on engaging both the assessor and assessee in the peer feedback process can be advantageous for the quality of students' peer feedback and written product in a wiki-based computer-supported collaborative learning environment in the first year of higher education. The main aim was to examine the effect of structuring the role of the assessee and/or assessor by respectively providing them with a peer feedback request and/or content checklist, together with a structured peer feedback template. The present study adopted a 2x2 design, in which four conditions were compared: (1) a control condition, (2) a feedback request condition, (3) a content checklist condition, and (4) a combination (feedback request + content checklist) condition. Every student (N=125) belonged to a group (n=27) of five and had to fulfil three consecutive assignments, each consisting of writing an abstract for a scientific paper in the wiki. The results revealed that the quality of both peer feedback and the final product increased for all conditions over time, but no significant differences were found between the conditions at time 2 and time 3. However, when the role of the assessee is structured to request for particular peer feedback, this appeared to be favourable for the peer feedback scores, but only at the initial stage of performance. Building on this, limitations, practical implications, and directions for future research are presented.