The rise of networked computers has made it possible to codify, store, and share certain kinds of knowledge more easily and for less cost than ever before. With computer-based information technologies playing an increasingly important role in how organizations store knowledge, electronic databases for people to share knowledge and information have become even more widely available. Despite the benefits of codification as a knowledge-sharing mechanism, it can be costly and difficult to develop, adopt, and maintain a database of such codified knowledge. Given such costs and difficulties, it becomes critical to identify when it is effective to use codification as a knowledge-sharing mechanism. There has been a lack of focus in prior research on examining the portfolio of both formal and informal knowledge-sharing mechanisms available for organi- zations, and on examining whether there are circumstances in which knowledge-sharing mechanisms other than codification may have been more effective in the first place, considering the cost of codification. This study thus examines codification and personalization (sharing of knowledge through direct person-to-person contacts) as two types of knowledge-sharing mechanism. Focusing on the codification versus personalization dimension of knowledge-sharing mechanisms, we examine the conditions that affect when it is more effective to use a codification approach versus a personalization approach for knowledge sharing in project-based knowledge work. We hypothesize that knowledge equivocality, task frequency, knowledge-seeker’s social network, and knowledge stickiness will affect the effectiveness of these two types of knowledge-sharing mechanism. The hypotheses are empirically tested in a professional service firm that builds up its knowledge and capabilities through conducting project work.