Inter-customer interactions are important to the operation of self-services in retail settings. More specifically, when self-service terminals are used as part of customers’ checkout processes in retail operations without the explicit involvement of retailers as the direct service providers, inter-customer interactions become a significant managerial issue. In this article, we examine the impact of inter-customer interactions at retail self-service terminals on customers’ service quality perceptions and repeat purchase intentions at retail stores. We conduct a scenario-based experimental design (N = 674) using a 2 × 2 factorial design in which inter-customer interactions are divided into “positive” vs. “negative” and occur during the “waiting” or during the actual “transaction” stages of self-services at a retail store. We use attribution theory to develop the hypotheses. The results demonstrate that, through their interactions, fellow customers can exert influences on a focal customer's quality perceptions and repeat purchasing intentions toward a retail store. Furthermore, these influences were impacted by how customers attribute blame or assign responsibility toward the retail store. Service operations managers should leverage these interactions by designing into self-service settings the capacities and interfaces that are best suited for customers’ co-production of their self-service experiences.