This article aims to understand the pathways through which financial vulnerability affects children’s social, emotional and behavioural (SEB) well-being and whether that impact is directly experienced or, as hypothesised, indirectly through their mothers’ emotional well-being. It uses data from Growing Up in Scotland – a longitudinal birth cohort study of 5217 children born in 2004–2005. The results show that maternal emotional distress is strongly associated with financial vulnerability, more so than with income, and that child SEB well-being is negatively associated with financial vulnerability and maternal emotional distress, with two-thirds of the effect of financial vulnerability being experienced indirectly through maternal emotional distress. While the qualitative evidence shows that financial vulnerability adversely affects older children directly, through the comparisons they make to their reference group, the quantitative finding is that young children are also negatively affected but predominantly via the effect of financial vulnerability on their mothers’ emotional distress.