Test anxious students experience worries and fears that prevent them from performing well on exams. In this study we describe the communication networks of students in a large lecture course and test the hypothesis that naturally occurring supportive communication reduces uncertainty and helps test anxious students improve exam performance. Findings indicate the relationship between support and test performance depends on a student's level of test anxiety and on the source of support. For students with high test anxiety, support from people outside of class is positively related to exam grades, and support from peers in class is negatively related to exam grades. The reverse is true for students with low test anxiety. The mediating role of uncertainty was not supported.