This study investigates knowledge transfer and knowledge building at three technical support centers (TSCs) which have been offshored to China. Utilizing an interpretive case study approach, the study examined how organizational knowledge was transferred from the US-based onshore TSC to a China-based offshore TSC, and how China-based knowledge was built and expanded in a dynamic changing business context. A model is presented which was developed from qualitative analysis of the field data, and this model aids understanding of how knowledge was transferred and built at the individual level, the group level and the organization level at the China-based offshored TSC. The shared mental models of the people in the organizations helped individual knowledge to be linked to group knowledge, and then to organizational knowledge. The ongoing informal communication, close interaction and coordination between onshore and offshore group members facilitated the knowledge transfer from onshore to offshored TSC. The model presented also demonstrates the knowledge flow through knowledge intermediaries in the offshored knowledge transfer and building processes, and provides new insights into organizational learning in an offshored business context.