This study investigates the relationships between U.S. buying firms' supplier development efforts, commitment, social capital accumulation with key suppliers, and buying firm performance. We identify linkages between supply chain management research on supplier development and organization theory research on social capital to consider how buying firm commitment to a long-term relationship, cognitive capital (goals and values), structural capital (information sharing, supplier evaluation, supplier development), and relational capital (length of relationship, buyer dependency, supplier dependency) are related to buying firm performance improvements (cost improvements, and quality, delivery, flexibility improvements). Analysis of buying firms from the U.S. automotive and electronics industries provides support for the theory that buyer commitment and social capital accumulation with key suppliers can improve buying company performance. Moreover, the findings suggest that the relationships of structural and relational capital vary depending on the type of performance improvement considered. #

A supply base is defined as the portion of a supply network that is actively managed by a buying company. The buying company, referred to as the focal company, manages the suppliers in the supply base through contracts and purchasing of parts, materials, and services. To facilitate better management of a supply base, we observe ''complexity'' as a key area of managerial consideration and apply the literature on complexity to the supply base. Supply base complexity is conceptualized in three dimensions: (1) the number of suppliers in the supply base, (2) the degree of differentiation among these suppliers, and (3) the level of inter-relationships among the suppliers. Four propositions have been formulated in terms of four major areas of research within supply chain managementtransaction costs, supply risk, supplier responsiveness, and supplier innovation. Corollary propositions are also stated. Although a reduction in complexity may lead to lower transaction costs and increased supplier responsiveness, in certain circumstances it may also increase supply risk and reduce supplier innovation. Therefore, reducing supply base complexity in general may be a costefficient approach, but blindly reducing it may potentially decrease the buying company's overall competitiveness. #

a b s t r a c tAcademics have increasingly recognized the benefits derived from social networks embedded within companies' buyer-supplier relationships. However, prior research has only examined the influence of social capital elements on performance, either individually or in part. We propose an integrative model examining the relationships among relational, structural and cognitive dimensions of social capital, and between these dimensions and the cost and innovation performance of the firm. A sample of 163 buyer-supplier relationships is used to test the model. Regression results indicate that the relational dimension of social capital fully or partially mediates the effect of the cognitive dimension on performance, and partially mediates the link between the structural dimension, operationalized as social interaction ties, and innovation performance. Further, high levels of legal bonds were found to moderate the relationship between the relational dimension of social capital and performance outcomes. Implications for theory and managers are discussed.Crown