This study explored the implicit brokerage positions of social network behind knowledge sharing and demonstrated applicability to researches of community of practices. A concept of knowledge brokerage was proposed on the basis of the theory of social brokerage, and hypotheses were developed to verify the relational properties of brokerage opportunities. Social network analysis (SNA) was applied to conduct the egocentric network surveys and related analyses. Several new ways of evaluating the performance of knowledge sharing have been developed. The results verified the usability of brokerage as indicators of knowledge sharing. The results also can reveal efficiencies and deficiencies in knowledge dissemination among members of communities. These findings hold relevance for studies on the information technology practices of other professionals.