The research aimed to evaluate an exploratory Compassion Focused Group Psychotherapy Programme and the impact on participants' experiences of self-criticism, usage of services and general wellbeing. Participants included patients with a history of complex attachment and relational trauma (A&RT), who might attract a diagnosis of personality disorder. This study utilised a quasi-experimental non-randomised within subject controlled design for the evaluation of the efficacy of the programme. Participants were recruited from tertiary care services. The programme consisted of a 12-week Preparation and Engagement intervention (PEG) which was Compassionate Mind Training and Psychoeducation, followed by a 40-week Compassion Focused Trauma Group intervention. The cohort was then followed up after 12 months during which period they received treatment as usual. A comprehensive selection of self-report measures was administered at various points during the therapeutic process and following completion of the group interventions. The results of the research showed that the provision of a long-term, slow-paced, Compassion Focused Group Psychotherapy intervention, resulted in significant changes across all measures which were maintained at 12-month follow-up. These significant results were maintained following intention to treat and reliable change analyses. These data were supported by a significant reduction in service usage and a significant increase in engagement in employment and education. This study has identified that within Compassion Focused Group Psychotherapy, there is a therapeutic process of establishing group-based safeness as a necessary precursor to cultivating compassion and reworking early shame-based trauma memories.