There is increasing evidence for the efficacy of non-medical strategies to improve mental health and well-being. Get into Reading is a shared reading intervention which has demonstrable acceptability and feasibility. This paper explores potential catalysts for change resulting from Get into Reading. Two weekly reading groups ran for 12 months, in a GP surgery and a mental health drop-in centre, for people with a GP diagnosis of depression and a validated severity measure. Data collection included quantitative measures at the outset and end of the study, digital recording of sessions, observation and reflective diaries. Qualitative data were analysed thematically and critically compared with digital recordings. The evidence suggested a reduction in depressive symptoms for Get into Reading group participants. Three potential catalysts for change were identified: literary form and content, including the balance between prose and poetry; group facilitation, including social awareness and communicative skills; and group processes, including reflective and syntactic mirroring. This study has generated hypotheses about potential change processes of Get into Reading groups. Evidence of clinical efficacy was limited by small sample size, participant attrition and lack of controls. The focus on depression limited the generalisability of findings to other clinical groups or in non-clinical settings. Further research is needed, including assessment of the social and economic impact and substantial trials of the clinical effectiveness and cost-effectiveness of this intervention.