Peer-feedback can be an effective method to support learning. However, students often require instructional support to provide and process peer-feedback effectively. Previous research used various types of instructional support to improve the quality of peer-feedback processes and outcomes. Yet, a comprehensive overview over their effects is missing. Therefore, this meta-analysis (based on N = 32 studies with N = 3806 learners) investigates the effects of different kinds of instructional support (feedback provision vs. feedback reception; content-specific vs. generic) on peer-feedback processes (formulating high-quality feedback messages, or effectively reflecting on the feedback received) and outcomes (subject-matter-related knowledge). Overall, peer-feedback with vs. without instructional support had a substantial positive effect (g = 0.47). Furthermore, we found a positive effect of feedback provision support on the quality of feedback provision (g = 0.72) and the quality of feedback reception (g = 0.69) but not on subject-matter-related knowledge. For feedback reception support, we found no effects on peer-feedback processes and outcomes at all. During feedback provision, content-specific support positively influenced the quality of feedback provision (g = 0.75) but not subject-matter-related knowledge, while generic support exerts a positive impact on the quality of feedback provision (g = 0.70) and subject-matter-related knowledge (g = 0.55). During feedback reception, we again found no significant effects of content-related support and generic support at all. The lack of effects for feedback reception support may be related to the limited number of studies on feedback reception in general. Finally, concrete implications and suggestions for future research are provided.