This study examined how perceived team characteristics, such as team efficacy and perceptions of politics within the team, influence organizational citizenship behavior (OCB) and deviant behavior through the mediating role of members' positive psychological capital. Team efficacy, defined as the belief in a team's capabilities, was predicted to have a positive effect on positive psychological capital, while perceptions of politics within the team—the perception that politics are pervasive within the team—was predicted to have a negative effect on positive psychological capital. Additionally, members' positive psychological capital was predicted to elicit positive behaviors such as organizational citizenship behavior and reduce negative behaviors such as deviant behavior. In particular, it was predicted that positive or negative perceptions of the team would influence organizational citizenship behavior and deviant behavior indirectly through members' positive psychological capital, rather than having a direct effect. To test these hypotheses, structural equation modeling was employed with a sample of 348 employees from two companies. The results showed that team efficacy had a significant positive effect on members' positive psychological capital, whereas perceptions of politics within the team did not have a significant effect. Furthermore, positive psychological capital had a significant positive effect on organizational citizenship behavior while having a significant negative effect on deviant behavior. Notably, positive psychological capital was found to serve as a full mediator in the relationships between team efficacy and the two outcome variables.