In order to optimize students' peer feedback processes, this study investigates how an instructional intervention in the peer assessment process can have a beneficial effect on students' performance in a wiki environment in first-year higher education. The main aim was to study the effect of integrating a peer feedback template with a varying structuring degree. The present study involved three conditions: a no structure, a basic structure and an elaborate structure condition. Due to a clear hierarchical structure, in which over time (level 1), 168 students (level 2) are nested within 37 groups (level 3), multilevel analysis was performed to examine the effect of time, student and group level influences on students' peer feedback quality and product scores. The results revealed that both peer feedback quality and product scores increase significantly for all conditions over time, after multiple practice occasions. In addition, after several practice occasions, significant differences were found between the conditions in both peer feedback (elaborate higher than no structure) and product scores (elaborate and basic higher than no structure). Building on this, limitations, directions for future research and practical implications are presented.