This article examines the association between mothers’ social assets and child social, emotional and behavioural (SEB) wellbeing for children living in a family with a persistently low income. The results show that low income is associated with lower social assets and lower SEB wellbeing in children; however, mothers living with a persistently low income but who have high social assets are significantly associated with higher levels of SEB wellbeing in their children, an interaction that is not significant for any other income quintile. Additionally, many of the sociodemographic variables assumed in the literature to be important in terms of child SEB wellbeing, such as family composition, young motherhood and maternal ethnicity, reduce in significance once income and mothers’ social assets are taken into account.