Cognitive-behavior therapy (CBT) for Social Phobia is effective in both group and individual formats. However, the impact of group processes on treatment efficacy remains relatively unexplored. In this study we examined group cohesion ratings made by individuals at the midpoint and endpoint of CBT groups for social phobia. Symptom measures were also completed at the beginning and end of treatment. We found that cohesion ratings significantly increased over the course of the group and were associated with improvement over time in social anxiety symptoms, as well as improvement on measures of general anxiety, depression, and functional impairment. In conclusion, findings are consistent with the idea that changes in group cohesion are related to social anxiety symptom reduction and, therefore, speak to the importance of nonspecific therapeutic factors in treatment outcome.