ABSTRACT: We study factors that promote knowledge sharing in a professional service firm. We performed two laboratory experiments with MBA students acting as participants. Our results indicate that an incentive must be considered sufficient to promote full knowledge sharing regardless of the incentive's type (monetary or nonmonetary). However, we find that the nonmonetary incentives used in our experiment were not deemed sufficient when participants self-determined incentive sufficiency. Additionally, when the peer environment promoted knowledge hoarding, knowledge sharing dropped the most when incentives were initially deemed sufficient. Finally, we find that competitive individuals are active sharers of valuable, proprietary knowledge only when heir competitiveness is team-oriented. To promote knowledge sharing, our results suggest careful monitoring of perceived incentive sufficiency, especially in the case of nonmonetary incentives, and a culture that directs employee competitiveness between teams.