Background and Method: This naturalistic study was undertaken in routine settings and compared the clinical effectiveness, costs, treatment preference, attrition and patient satisfaction of Group and Individual CBT. Results: No significant differences were found in depressive and distress symptoms between group and individual CBT at post-treatment and follow-up. Individual CBT was 1.5 times more expensive to provide than Group CBT and the wider costs of other supports were similar between study arms suggesting a cost-effectiveness advantage for Group CBT. Patients preferred individual treatment at baseline but, despite this, there were no between-group differences in attrition or satisfaction. Conclusion: A larger RCT study is needed, but running CBT groups for depression could be considered more frequently by clinicians.