The current systematic review examined the similarities and differences between mothers’ and fathers’ reported barriers and facilitators to engaging in family-based interventions for child and adolescent behavioural problems (aged 2–17 years). Systematic searches of six electronic databases and grey literature alongside a two-way screening process identified twenty eligible qualitative studies from 2004 to 2019. A thematic meta-synthesis identified similarities in major themes of psychological, situational, knowledge/awareness, programme/intervention, co-parenting, practitioner, and beliefs/attitudes factors, alongside group experiences and stages of engagement. However, differences emerged in subthemes related to parental, treatment, and service delivery factors that included individual ideologies of parenting, parental roles, and treatment participation; the role of mothers in facilitating engagement; and individual preferences for treatment content and delivery. Overall, findings suggest that while mothers and fathers experience similar challenges to engagement, they can also experience distinct challenges which need to be addressed at the treatment outset to maximise engagement.