Families that have care and protection concerns are considered a high-risk cohort due to multiple risk factors such as psychosocial and socioeconomic stress and mental health concerns, which greatly increase the probability of child maltreatment. For this reason, many parents involved with child protection services have limited or no contact with their children, yet may still be expected to engage in parenting programmes as part of reunification plans. This study examined the efficacy of ParentWorks, a 13-week parenting programme based on the Positive Parenting Programme (Triple P; Sanders, 2008) and specifically adapted for high risk parents in Aotearoa New Zealand with care and protection concerns. This study employed a two-phase mixed methods research design. Quantitative data included pre- and post-programme measures of participant mental health (depression and anxiety) and stress (general tension/stress and parenting stress) from the last five years of the programme. Qualitative data, gathered through semi-structured interviews, examined recent participants’ reflections of the programme shortly after completing it, and their subjective accounts of changes in mental wellbeing and stress. Results from the quantitative analyses showed a nonsignificant trend towards improved mental health, with significant changes in participants’ self-reported stress. The findings from the qualitative data identified five themes from the interviews: programme benefits, applied learning, group connectedness, self-image, and general thoughts and suggestions for ParentWorks. Taken together, these results suggest that ParentWorks is effective in reducing stress symptoms among participants, while changes in mental health may be indirect and do not seem to be as closely connected with course participation. The findings are discussed in light of their consistency with prior literature showing quantitative analyses in similar populations and their fit with a meta-synthesis of parents’ qualitative experiences of parenting programmes. Finally, an application of a logic model from Triple P research is considered in relation to the ParentWorks programme, allowing exploration of potential areas for growth.