How knowledge management contributes to performance is a vital question in professional service firms(PSFs).Based on an organization knowledge creation theory,this paper integrates sociology and economics paradigms to propose a knowledge management model in PSFs.Evidence from 327 PSFs in China supports our theory.The results show that:(1)individual knowledge codification(i.e.individual knowledge structuring and individual knowledge externalization)is positively related to service performance,(2)organizational knowledge codification(i.e.organizational knowledge structuring and organizational knowledge externalization)is positively related to service performance,(3)the interaction of individual knowledge codification and organizational knowledge codification is significantly related to service performance.This study develops the organization knowledge creation theory and advances research on knowledge management in PSFs.