Eamonn is on the academic staff of the National Institute of Technology Management (NITM) in University College Dublin (UCD), and is active in teaching, research and the business development activities of the Institute. Prior to joining UCD, he was Engineering Director for Bristol Myers Squibb, and was responsible for the design, installation and maintenance of process plants for developing and manufacturing anti-cancer drugs. He also worked as a consultant advising major multinationals and government agencies in asset management and procurement process improvement.Eamonn researches in the area of supply chain relationship management and has published in the International Journal of Operations & Production Management. He is on the leadership team of the IBM Integrated Supply Chain Research Consortium, a group of supply chain experts drawn from universities in the US, Europe and Asia, and is currently working with IBM on a global study of supply relationship management. In addition to teaching on a range of operations and supply chain programmes, Eamonn has a particular interest in the development and delivery of Service Supply Chain programmes, both academic for-credit modules and executive education seminars.2 Abstract Purpose -The paper employs transaction cost theory and social exchange theory to compare how buyers and suppliers perceive relationship mechanisms. The paper also explains the antecedents and dynamics of relationship performance by comparing buyer and supplier perceptions of the same relationships. Within the study we specifically focus on the issue of relationship success and test the hypothesis that the antecedents of perceived relationship success for buyers differ from those of suppliers within supply chain relationships.Design/methodology/approach -The paper is based on a study of the supply chain relationships of a major ICT company where matched pairs of buyers and suppliers were surveyed on the nature of their relationships. The survey instrument drew from previously published constructs on key relationship dimensions such as trust, commitment, power, communication, uncertainty and performance. A series of nested models were then developed and tested for the two groupsbuyers and suppliers.Findings -The study found that buyers and suppliers have significantly different perceptions of their relationships across a range of dimensions. In addition, the antecedents of relationship success for both groups bear little similarity, thus supporting our hypotheses.Implications -This research has implications both for academics and practitioners. For academics, the contribution of the paper is in establishing how both transaction cost theory and social exchange theory factors are perceived in dyadic relationships. Specifically, the paper has implications for the study of supply chain relationships as it highlights the perceptual gaps between buyers and suppliers and differences in the drivers of relationship performance. For practitioners, there are implications for managing supply chain relationship...