In a refrigerated warehouse, workers organize distribution and exchange of frozen seafood by the spatial and temporal arrangement of loads. Using videotapes of workers' activities and interviews, this paper investigates how workers organize space, time and artifacts in the activity of frozen seafood distribution and exchange, and how organized space, time and artifacts systematize workers' multiple courses of actions and give direction to them. Particular attention is paid to how the workers use artifacts such as various documents and computers as part of their practices, because the activity of distribution and exchange in this workplace is regarded as the activity of organizing space and time with various artifacts in multiple contexts. Through the analysis of situated literacy of using artifacts, it was shown that the activity of using artifacts is always embedded in multiple contexts. At the same time, diverse artifacts organize multiple contexts of work. Thus, there is the reflexive interaction between the artifacts and the contexts.