Several studies have pointed to the benefits of learning in groups. However, surprisingly little research has been conducted regarding what role relationship-related personality traits play in the effectiveness of this kind of student learning. Such personality factor can potentially buffer the students' effectiveness in groups. The present study focused on attachment orientations--personal characteristics of individuals that reflect internal models of relationships--and assessed their impact on different aspects of students' feelings and functioning in higher-education study groups. It was hypothesized that individuals with interpersonal difficulties (characterized by high attachment anxiety or avoidance) will not benefit from a learning group and that they may exhibit poorer performance in group projects. Participants (N = 244) were college students enrolled in courses that included a group project. They completed measures of their attachment orientations, instrumental and socio-emotional functioning in the group, and satisfaction from the group. Additionally, their GPA and grade in the group project were assessed. Results indicated negative associations of attachment anxiety and avoidance with students' self-reported instrumental and socio-emotional functioning in the group. However, attachment anxiety was associated with higher grades in the group task. Attachment avoidance was not associated with students' grades. The study's findings generally suggest that attachment insecurities do not obscure students' actual performance in group projects, contrary to students' self-perceptions. Implications for group learning are discussed.