An emerging body of literature identifies a connection between mutual learning and co-design, it does not specify the nature of this connection or its implications for the practice of co-design. In this paper we explore the theoretical and practical implications of specifically focusing on mutual learning in co-design. We present three case studies with rural communities in the Highlands and Islands. Using participatory action research, we undertook a series of co-design projects with each case forming an action research cycle. Through these we build cycles of insights concerning collaborative learning and how this can contribute to practical co-design outcomes for participants. We also present insights that increase the duration and amount of mutual learning in co-design projects.