Buyer-supplier relationships are characterised by relational norms. These norms are bilateral expectations that can reduce opportunistic behaviour, improve value creation and develop cooperation among exchange parties. Drawing on relational exchange theory, this study explores how three relational norms, solidarity, power and flexibility are interrelated in supply chain relationships. We test a mediated model where solidarity and power directly impact relational performance and flexibility mediates these relationships. The mediated model was tested with matched pairs of data on 93 supply chain arrangements between buyer and supplier organisations. Results show that solidarity improves relational performance both directly and in the presence of flexibility. Power, on the other hand, does not impact relational performance, both directly and through flexibility. The results obtained, especially the importance of flexibility and solidarity for both buyers’ and suppliers’ managers in maintaining long-term benefits in supply chain exchanges, are discussed for theory, practice and research.