Despite the importance and popularity of the satisfaction construct in service research, the influence of individuals on a customer group remains poorly understood. Only recently, the influence of an individual group member on other customers’ service perception has found its way into service management literature. A growing body of research now deals with customer – to – customer interaction (CCI) and focuses on the impact individual customers have on services that are delivered to other individual customers. Very little is known about the different roles within these groups in a service experience. In recent management literature, leadership has been examined in classical employee – manager relationships. In services marketing publications there appears to be a lack of research on the influence of different customer roles on a service encounter. In this paper we set out to examine the role an informal leader takes in customer groups. Specifically, our purpose is to explore how leadership of the informal leader influences 1) satisfaction with him and with the service and 2) how customer – to – customer interaction mediates this relationships. The hypothesized relationships between satisfaction with the service, satisfaction with the informal leader, leadership behaviour, and CCI are tested in a structural equation model. Drawing on a sample of 225 customers who have experienced a group service we demonstrate that leadership behaviour of an informal leader has a negative and satisfaction with the informal leader has a positive effect on satisfaction with the service. Additionally, we confirm that this leadership behaviour has a positive effect on customer – to – customer interaction and we examine the mediating role of CCI within the relationship between leadership behaviour and satisfaction. All constructs meet the AVE and the Fornell-Larcker criterion, and the fit indices are good, suggesting a reliable and valid model.