ABSTRACT Objective: To examine qualitatively changes occurring in discussions within a time-limited psychotherapy group for mothers with post-natal depression. Method: Discussions occurring in a group that comprised five mothers and a therapist were recorded over the course of six one-hour therapeutic sessions. Participants had been referred or had self-referred to the group on the basis of having post-natal depression. The recorded discussions were transcribed and then analysed in accordance with principles of conversation analysis. Results: Analysis of early and later group discussions showed changes in group members’ alignment with the topics that were introduced, in turn-allocation and turn-taking, and in the co-construction of accounts of experience. In contrast to early discussions, in later discussions participants aligned with topics relating to personal emotions, self-selected as next speakers in the discussions, and collaboratively worked up accounts that made sense of their experiences of childbirth and of being diagnosed as having post-natal depression. Conclusions: Interactional changes over the duration of the group point to the benefits for mothers with post-natal depression of participating in a time-limited psychotherapy group. Fine-grained analysis of group discussions potentially offers a way of examining changes over time in psychotherapeutic groups more generally.