BACKGROUND: Developmental monitoring, performed using culturally relevant tools, is of critical importance for all young children. The ASQ-TRAK is the culturally and linguistically adapted Ages and Stages Questionnaire (ASQ-3), a developmental screening tool, for Australian Aboriginal children. While the ASQ-TRAK has been well received in practice, investigating its psychometric properties will enable professionals to make informed decisions about its use. AIMS: To conduct a rigorous validation study of the ASQ-TRAK by applying Kane's argument-based approach. SUBJECTS: The ASQ-TRAK, Bayley-III and/or BDI-2 were administered cross-sectionally to 336 Australian Aboriginal children aged 2-48 months across ten participating sites in the Northern Territory and South Australia. A sample of staff and caregivers completed feedback surveys about the ASQ-TRAK. RESULTS: ASQ-TRAK domain scores were moderately positively correlated with corresponding domain scores on the Bayley-III or BDI-2. Inter-rater and inter-instrument reliability were high. Sensitivity (83%), specificity (83%) and negative predictive value (99%) were acceptable. Staff and caregivers expressed high levels of satisfaction with the ASQ-TRAK. CONCLUSIONS: Regular developmental screening can provide important information about developmental vulnerability and the need for services. The ASQ-TRAK should be administered by trained Aboriginal community-based workers and the implementation approach carefully planned. Areas for future research include longitudinal follow-up of children, investigating existing norms and cut-off scores, and considering the appropriateness of the ASQ-TRAK with Aboriginal people from different locations. The ASQ-TRAK has the potential to fill an important gap by enabling better access to high-quality developmental monitoring and targeted early intervention.