Past studies on organizational behavior or industrial psychology found work-related attitude crucial for the performance and success of organizations, whereas the industrial organization studies emphasized the importance of team operations and focused on the peer interaction among team members in the workplace. This study attempts to bridge the gap in the two parallel literature by investigating the determining factors for the performance of the extension department in Taiwan farmers’ associations (TFAs). The results in this study indicate that work-related attitude reflecting the extension personnel’s willingness to devote time and efforts as well as their holding high self-expectation for themselves and work, have positive influence on both the group and individual performances. Nonetheless, attitudinal contagion is found to have a significant adverse effect on group performance. This result suggests the need to pay close attention to individual employee’s job satisfaction even in the non-profit organizations like TFAs. Moreover, a routine monitor of the work atmosphere or one-by-one consultation with the extension personnel can improve their performance.