A key challenge facing the mental health field is connecting children and families to services when symptoms first appear. Multiple barriers inhibit timely access to treatment, and interventions to resolve barriers to care are not common among health and social care organisations. To address this research-to-practice gap this study undertook a scoping review of the empirical literature aimed at identifying key factors in the social ecology of families which influence family engagement with child and adolescent mental health services, then identifying and describing models of intervention designed to help facilitate access to care. Forty studies published between 1 January 2000 and 28 February 2019 were reviewed. Key factors associated with child and adolescent mental health service engagement included family attitudes towards mental illness and help seeking, the flexibility and availability of needed services, community attitudes and stigma surrounding mental illness and mental health treatment, and the degree of coordination and integration across systems of health and social care. Models of intervention to facilitate engagement with mental health services included family outreach, telephone and digital health strategies, and integrated care approaches. Empirical support is strongest for family outreach and integrated care, although telephone and digital health strategies are underexplored with children and families and a potentially promising avenue for future research. To support family engagement with child and adolescent mental health services health and social care organisations should be prepared to identify barriers in their local practice settings and integrate efficacious engagement approaches into their continuum of available services.