Aim: To explore the causal pathways leading to poor birth outcomes among a cohort of Aboriginal infants.Methods: A cross-sectional study was conducted. Data were collected via face-to-face interviews conducted 6-12 weeks post partum and links to the WA Midwives' Notification System. Two hundred and seventy-three Aboriginal infants and their families from Perth, Western Australia were recruited in the mid to late 1990s.Results: Poor birth outcome was defined as low birth weight and/or preterm birth. Criteria for poor birth outcome were met by 12.3% of the cohort. A history of maternal hypertension, vaginal bleeding and consumption of excess spirits in pregnancy were independent predictors of poor birth outcome. Mother being raised on a mission, maternal education, smoking during pregnancy and being exposed to passive smoke during pregnancy were also important risk factors.Conclusions: Results indicate that maternal social exposures, maternal ill-health before the index pregnancy and maternal ill-health during the index pregnancy are all important contributors to poor birth outcomes for urban Aboriginal infants. While the causes of poor birth outcomes are complex, the current study highlights several areas where preventive measures may be useful.