The ability of personality and cognitive ability to predict perceptions of group influence in small work groups are assessed both in initial and advanced stages of group formation. Extraversion is found important to initial perceptions of intra-group influence, which is partially mediated by peer-perceived social-emotional usefulness. After a few months, reputations are established and everyone has met; now work needs to get done efficiently and accurately and cognitive ability predicts increases in perceived group influence, which is partially mediated by perceived intelligence. After even more time, other Big Five personality traits become important to changes in perceived group influence, with positive associations with openness to experience, and negative associations with neuroticism and conscientiousness. The study findings and implications are discussed.