Background: Psychoeducation provides a range of benefits to service users with severe mental health illness and their family members. A lack of engagement with mental health services may lead to poorer outcomes and increased healthcare costs. Few studies have explored the problem of engagement in relation to group psychoeducation from a multi-site and multi-stakeholder perspective. Methods: The aim of the study was to explore the factors influencing service user and family engagement with group psychoeducation programmes. The study design was qualitative descriptive. Data were collected through individual and focus group interviews with key stakeholders (n=75) involved with the programme within 14 mental health sites in the Republic of Ireland. Results: Enablers and barriers to engagement were identified at participant, provider and programme level. Motivated participants and clinicians, peer co-facilitation and support, and skilled and responsive facilitators were some of the factors which enhanced engagement. Barriers to engagement included a lack of motivation and readiness among participants, concerns related to stigma and confidentiality, a lack of support for programme participation within families, group discomfort, issues with accessing transport, the time and length of the programme being unsuitable for some participants and a lack of capacity among clinicians.Conclusion: Findings from the study illustrate the multifaceted nature of engagement as well as provide a greater understanding of the multifactorial influences on engagement. Strategies to enhance engagement should therefore reflect a multipronged approach. At the outset of programme implementation, organizations should address their readiness to engage, conduct local needs assessments to anticipate individuals’ needs and plan accordingly in order to maximize engagement, and bolster facilitators’ engagement skills through the provision of training and mentoring opportunities.