This study investigated the social network structure of booking officers at the Honolulu Police Department and how the introduction of an online discussion tool affected knowledge about operation of a booking module. Baseline data provided evidence for collaboration among officers in the same district using e-mail, telephone and face-to-face media but showed minimal collaboration between officers in different districts. On average, knowledge of the booking module was low. After introduction of the online discussion tool the social network structure changed, showing an increase in collaboration between different districts and an increase in knowledge of the booking module, even though frequency of collaboration did not increase significantly. The study suggests that the formation of new collaborative ties is more significant for learning through information sharing in social networks than raw frequency of interaction. This work is framed by theories of knowledge building, social architecture, and communities of practice. (Contains 4 tables and 4 figures.)