Background Early identification and intervention for mental health (MH) problems in childhood offers lifelong benefits. Many children with MH problems do not receive appropriate help. To address this need, an online universal MH screening tool, the Growing Minds Check-In for parents/caregivers (GMCI-P), was developed to provide feedback to parents on their children's MH, identify children at risk of MH problems, and link parents to evidence-based online programs/information, with the goal of facilitating parent help-seeking, and ultimately reducing the prevalence of child MH problems.

Methods/design A randomised controlled trial (RCT) with 440 parents/caregivers will be conducted to 1) examine the efficacy of GMCI-P for increasing parent help-seeking; 2) explore acceptability; and 3) cost-effectiveness. Participants will be Australian parents/caregivers with a child aged from birth to 17 years, 6 months, who will be randomly allocated to GMCI-P (intervention) or waitlist control (WLC) group, and complete baseline measures. The intervention group will complete the GMCI-P immediately, the post-GMCI-P intervention questions, a three-month and six-month follow-up. The WLC group will receive access to GMCI-P after their three-month follow-up but will not be followed up further. The primary outcome is parent help-seeking behaviour for child MH, and secondary outcomes include child MH, parenting, parent wellbeing, acceptability, cost-effectiveness, and unintended negative effects.

Discussion The results from this study will provide efficacy, acceptability and cost-effectiveness data on a universal online, parent-report child MH Check-In. These results can be used to inform public policy on universal screening for child MH.

Trial registration: ACTRN12624000098538