There were two objectives. First, to understand the variation of primary dentition caries among 4- to 8-year-old children in Qatar across nationality classified into four groups, and second, to explore whether the association persisted in the presence of socio-demographic and behavioural indicators. The study used data from the Qatar Child Oral Health Survey 2017 (QCOHS 2017). Detailed information was collected through a parental dual-language questionnaire and an oral epidemiological examination conducted by calibrated dentist examiners. Children in 20 kindergartens and 40 schools across Qatar were recruited. Data were weighted to represent the Qatar child population. Overall, 1154 children aged 4-8 years old (48.9% female, 51.1% male) participated. Qatari children made up 26.3%, Non-Qatari (N-Q) Arabic children 44.2% N-Q Indian sub-continent 16.4% and N-Q Other 13.1%. There were no significant differences by nationality for age or sex, but differences existed for kindergarten/school type and parents' highest level of education. Among behavioural indicators, Qatari and N-Q Arabic children began toothbrushing later, and more N-Q Other children brushed 2+ times a day and had made a check-up visit in the last 12 months. More Qatari children were in the highest tertial for sugar intake and drank bottled water with no fluoride. All N-Q children had a significantly lower prevalence and experience of caries. The means ratio (95% CI) for N-Q Arabic (0.78; 0.65-0.94), Indian (0.58; 0.46-0.72) and other children (0.61; 0.42-0.88) were all significant against Qatari nationality children. Multivariable models showed an attenuation of the association with caries with the means ratio for N-Q Arabic (0.92; 0.73-1.16), Indian (0.79; 0.57-1.11) and other children (0.94; 0.61-1.44) being non-significant compared to Qatari nationality children. The variables which were significantly associated with caries were parental education, toothbrushing frequency, sugar intake and check-up visiting in the last 12 months in the multivariable models. Primary dentition caries in children resident in Qatar differed by nationality. The association of primary dentition caries with nationality was markedly attenuated and non-significant in the presence of socio-demographic and behavioural variables, pointing towards the importance of these variables as the pathways to improving primary dentition caries prevalence and experience of children in Qatar.