In this paper, we explore the basic premise that IT service quality follows the structure of business/IT interactions and thus highlight an important organizational design issue in IT governance. Motivated by concepts used in social network theory we build a model that proposes a causal relationship between structural characteristics of social business/IT networks and IT service quality. The model is empirically evaluated and explained using case studies based on five interviews in three firms. Thus we extend the general assumption that the business/IT partnership is crucial for IT service quality by identifying structural characteristics of the network among and between business and IT staff which enhance this partnership. Important results are that strong and bridging ties at the business/IT interface are crucial for IT service quality and that a good integration of interface actors within their own unit supports IT service quality.