The success of the emerging service oriented computing relies fully on the Quality of Service (QoS). However, existing QoS techniques do not accommodate users' skills and preferences. We propose user-centered QoS, which is a QoS defined by the interaction between skills/preferences of service user(s) and quality of service provider(s). By implementing user-centered QoS approach, the best service is delivered to users based on the calculation not only the quality of the services but also the skill/information of users. We proposed a novel two-stage approach for combining services in user-centered QoS, i.e. intra-workflow and inter-workflow service selection. Intra-workflow service selection is used to calculate the most optimal QoS value for each composite service. Inter-workflow service selection is used to search for the most optimal combination of composite services by utilizing the QoS values obtained from intra-workflow service selection. In this paper, we provide a concrete example of user-centered QoS in the language services domain. This problem arises when there are multi users with different quality of English using multilingual chat service.