<p>Child and adolescent mental health disorders are twice as prevalent among families with low socioeconomic status, highlighting that these are the families who most need mental health services. Yet in these families, children and adolescents are less likely to receive mental health care, and even when they do, their outcomes are often poorer than those from families with higher socioeconomic status. The aims of this qualitative study were to identify barriers and facilitators to mental health service access and engagement for children and adolescents from families within the lowest quintile of Australian national household income. Employing a multi-informant focus group methodology, thematic analysis was conducted on four focus groups (total sample, <i>N</i> = 30) consisting of two groups with caregivers, one with adolescents, and one with mental health professionals. Themes included perceptions of service quality, service norms, scepticism and trust, mental health knowledge and communication, and the valued but overwhelmed nature of school-based services. Participants emphasized barriers more than facilitators. Findings suggest that commonly recognised barriers to mental health services may be particularly consequential within socioeconomically disadvantaged contexts, highlighting the urgency to (re)establish models of mental health care that can support the diverse needs of children and families with low socioeconomic status.</p>