BACKGROUND AND AIM: Evidence is growing on the adverse neurodevelopment effects of traffic-related air pollution in children. This study explored the role of multiple exposure periods based on residential proximity to roadways on behaviour and early development in children 13 years. METHODS: Data were from 2016/17 Mothers and their Children’s Health study, a sub-study from a prospective longitudinal study called Australian Longitudinal Study on Women’s Health (ALSWH). We geocoded mother’s residential addresses at each ALSWH survey wave since 1996, and calculated distance to major roadways including roadway density in 100, 200 and 500 metre buffers as measures of traffic-related air pollution. Child outcomes were maternal-rated behaviour problems (Strengths and Difficulties Questionnaire; SDQ, aged 2-12 years, n=5,471 children) and developmental delays in communication and gross motor (Ages and Stages Questionnaire; ASQ, aged 1-66 months, n=1,265 children). Defined exposure periods calculated were roadway proximity before birth, children’s lifetime, and mothers’ long-term exposure. We performed logistic regression to estimate odds ratio (OR) for each child outcome, adjusting for potential confounders. RESULTS:Although not statistically significant, children who lived ≤ 200m compared to 200m away from major roads had ORs1 for poor behaviour and gross motor delay across all periods of exposure. Similar findings were observed in fully-adjusted models for road density of all road types in 100 and 200m buffers. However, this was only present for two exposure periods, children’s lifetime and mothers’ long-term exposure to road proximity. Residing closer to roadways prior to birth was associated with behaviour problems (e.g. [OR 1.16; 95% CI 0.83- 1.62] and [1.39; 0.82- 2.34] for all road types and major roads only in 200m buffer, respectively). Findings were mixed for communication delays in younger children due to small sample size (n=57). CONCLUSIONS:No evidence of a significant association was present between road proximity and children’s behaviour and early development. KEYWORDS: Neurodevelopmental outcomes, Traffic-related, Epidemiology