Knowledge brokering teams are increasingly deployed in the public sector to promote coordination and integration across previously separated practices. Permeability of external boundaries surrounding such teams is, however, often taken for granted and has so far received relatively little attention. To address this gap, this article presents the findings of an in-depth longitudinal qualitative case study of a knowledge brokering team operating in the fragmented healthcare context. It argues that boundary spanning, which increases the permeability of the team boundary, can co-exist with the strategies of disengagement, such as boundary buffering and boundary reinforcement, which reduce permeability. The tension between these seemingly opposing strategies can be resolved through selective permeability, whereby the strength of the external team boundary varies depending on the out-group with which the team interacts, the out-group’s mode of participation, the individual boundary spanner(s) deployed and the stage of the boundary spanning project.