A main purpose of information systems (IS) is to support intra- and inter-organizational collaboration. From a collaboration perspective, information transfer gets a meaning if the transferred information is converted to knowledge. If we instead of an information perspective take a knowledge perspective on collaboration, stressing knowledge integration, many other factors than the IS itself and information characteristics will be critical. Working routines and the way information is interpreted, both by the sender and the receiver, will be stressed. Research focusing IS-supported collaboration and knowledge management is needed. This paper presents such an empirical study. Focus in the study is on knowledge integration between different self-contained work groups and the study explores how knowledge integration is accomplished and why the integration is not always simple and successful. The empirical context is the Swedish health care and more specifically, the daily knowledge integration between a microbiology laboratory and its customers. Empirical data was collected by interviews and observations, and analysed with help of a theoretical model constructed from two main theories: Community of Practice (CoP) and Knowledge Management Episodes. This model implies that knowledge should be seen as a process and in a relational perspective. The study shows that there is a mutual dependency between the IS and other knowledge resources in the organization. Even if the groups have the same overarching goals, regulations, and the same IS, the different groups create their own working routines, ways of interpreting information, and their own ways to convert information to knowledge. This situational and emergent development of work practice around IS suggests that management of existing IS and the implementation of new IS needs to stronger focus the mutual influence between IS and working activities and that feedback in the integration process is important.