Over the last decades, much research on peer learning practices has been conducted. Quantitative, experimental designs focusing on problems of cause and effect dominate. Consequently, effects on achievement are well documented, as is the influence of different conditions on the effect rate. In spite of the general acknowledgment of the importance of peer learning and a large amount of research on collective learning practices, questions regarding the quality of peer interaction, and how peer relations influence learning, are not well elaborated. This paper complements the discussion on effect focusing on the processes of interaction between peers, and relates these to theoretical perspectives on learning as fundamentally social. Inspired by meta-ethnography an integrative analysis across seven qualitative studies was accomplished. The approach enabled an investigation of peer interactions in different educational settings. The analysis elaborates on how instructional designs and students' relational knowledge mediate interaction in peer learning. The paper further discusses the potential of approaches synthesising qualitative studies as a tool in qualitative research. (Contains 2 tables.)