<p>Dialectical Behaviour Therapy (DBT) aims to help people live a life worth living. It has increasingly been developed and adapted to address a range of mental health symptoms across different ages, cognitive abilities and environmental contexts; however, its popularity in implementation has outpaced empirical research. The current study was a Process Evaluation which assessed professionals’ perspectives about a DBT-informed skills group called He Waka Eke Noa operating at Korowai Manaaki – a youth justice secure residence in New Zealand (NZ). The study involved 11 interviews with professionals across two organisations involved in facilitating He Waka Eke Noa and/or supporting the young people who participated. Thematic analysis was used to analyse the interviews and three overarching themes were identified. The first theme, ‘Factors influencing practical effectiveness’, explored areas which professionals highlighted as having a significant impact on how He Waka Eke Noa worked and had three subthemes: ‘Generalisability’, ‘Cultural Responsivity’, and ‘Criminal Justice Environment’. The second theme, ‘Theoretical application of DBT to young people in NZ’ investigated the compatibility of DBT with young people in secure youth justice residences in NZ. The final theme, ‘Motivation’, considered the role that motivation played in engagement and continuation of treatment for people involved in He Waka Eke Noa. The findings from this study shed light on how the group was operating and highlighted the importance of the relationship between facilitators and young people. It identified the challenges He Waka Eke Noa faced including the difficulty of balancing a risk-reduction approach with creating a therapeutic environment. Further developments are considered that would assist He Waka Eke Noa in maximising its effectiveness through increasing resources and ensuring diversity amongst the clinicians (e.g., increasing cultural diversity). The thesis concludes with recommendations for the future direction of operation, for example, rolling out DBT-informed skills groups in other residences and the community; and potential research avenues.</p>