BACKGROUND: This study compares oral health outcomes and behaviours for young Australian children by residential state or territory to determine whether state differences arise from individual exposures to risk factors. METHODS: Cross-sectional data for 4606 2-3 year olds and 4464 6-7 year olds were obtained from the Longitudinal Study of Australian Children. Outcome measures were parent-reports of children's caries experience, frequency of toothbrushing and dental services use. RESULTS: For 2-3 year olds, children from the Australian Capital Territory were less likely to have parent-reported caries than children from other states, and more likely to brush their teeth twice daily and to have used dental services. For 6-7 year olds, optimal outcomes were observed in New South Wales for lowest caries experience, Western Australia for highest toothbrushing, and South Australia for highest dental services use. Adjustments for socio-demographic predictors did not eliminate state differences in oral health. CONCLUSIONS: Large state differences in the oral health of young children persisted after adjustment for individual socio-demographic determinants, suggesting these arise from variations in the systems to promote and care for children's oral health. Several states would benefit from a stronger emphasis on oral health promotion in young children, and disparities from a young age suggest the need for better engagement of early childhood professionals in oral health promotion.