In this paper the authors explore customer and supplier relationships from the perspective of small firms (SMEs). They introduce the general supply chain literature and highlight some key problems when such theory is applied to understanding the practices of SMEs. In particular they introduce and critique current study focusing on the purchasing behaviour of small firms. This critique illustrates some key issues including the dominance of ideas that depend on the practices of large firms and the assumed homogeneity of the SME population. Following this critique the paper sets out a rationale for exploring what SMEs 'do' in terms of purchasing behaviour. The empirical studies outlined explore two groups of firms, a general control group across the SME population and a specific purposeful sample set in steel based manufacturing companies. The results illustrate the important role of social factors in the management of relationships.