The current study investigated the relationship between session impact and outcome in group psychoeducative CBT, conducted in a routine clinical setting. Participants completed a range of outcome measures at screening, start of the group, termination of the group and at the 3-month follow-up of the six-session intervention. At the end of each psychoeducative session, participants completed a group-specific version of the Session Impact Scale. No single psychoeducative session was seen to generate greater impacts than any other session of the six. Clients who experienced a clinically significant reduction in symptoms during the group perceived greater interpersonal impacts in the group. Results suggest that interpersonal aspects such as normalization may be the active ingredient of change in such service delivery settings. The results are discussed in terms of the potential powerful role of non-specific factors in such large groups and directions for further research examining the impact-outcome relationship in group-based CBT.