This article conceptualizes and empirically examines buyer-supplier relationships in respect of supply sourcing strategies, relationship characteristics and firm performance. Two sourcing strategies available to organizations are examined, critical and leverage, which in turn, influence the approach to managing the supplier relationship (arms-length or collaborative). We argue that different relationship approaches are appropriate to achieving different performance outcomes. A structural equation model, using a sample of 142 manufacturing firms based in the United Kingdom, is used to test this hypothesized model. The results indicate that a critical sourcing strategy requires collaborative supplier relationships in order to achieve higher relationship and business outcomes, while leverage sourcing strategies have a direct impact on these same performance outcomes. In addition, a leverage strategy was associated with increased levels of supplier power, though this power was found not to have a significant effect on performance. Our study provides support for the importance of aligning sourcing strategies to particular supplier relationship approaches in order to improve firm performance. Managerial implications of these findings and future directions for research are then offered. © 2006 British Academy of Management.