Evidence-based parenting programs (EBPPs) are recommended as a first-choice intervention in addressing child conduct problems, but positive outcomes achieved in controlled research environments are not always replicated within mainstream services, particularly when delivered in disadvantaged settings. This qualitative study, nested within a randomized controlled trial, investigated the barriers and facilitators associated with the implementation of the Incredible Years Parenting Program (IYPP) in five healthcare services based in disadvantaged areas in Ireland. We conducted semi-structured interviews with service managers (N = 5) and group facilitators (N = 11) who delivered the parenting groups. Interview data were analysed using grounded theory. The findings indicate that the key drivers of successful implementation include: (1) compatibility between intervention and agency goals; (2) intra- and inter-agency supports to enhance fidelity, retention of parents, and leverage of funding; and (3) careful attention paid to group composition and screening for parental readiness to attend the program. There was variability in the extent to which the IYPP was integrated into services and key challenges related to the retention of multiply-disadvantaged parents and sustainability issues. Reassuringly, the analysis also revealed measures by which such challenges may be addressed. This study is one of the first to investigate the agency processes and factors involved in implementing an EBPP with disadvantaged families in mainstream healthcare settings. In addition, there are a number of important generalizable lessons for the implementation and upscaling of EBPPs elsewhere.
