In this study, the authors investigate the relationships between team communication styles and job-related cognitions on one hand and knowledge-sharing attitudes and behaviors on the other using 424 members of different work-related teams. Both eagerness and willingness to share are positively related to knowledge sharing - both donating and collecting knowledge. These attitudes mediate the relationships of communication styles, job satisfaction, and performance beliefs with knowledge-collecting and donating behaviors. In terms of team communication styles, an agreeable style is positively related to team members' willingness to share their knowledge, whereas an extravert communication style of a team is positively related to both eagerness and willingness to share. Performance beliefs and job satisfaction are both related to willingness and eagerness to share knowledge. However, in contrast with the authors' expectations, the relationship between eagerness to share knowledge and knowledge donating is not stronger than the one between eagerness and knowledge collecting. © 2006 Sage Publications.