Using data from the 1970 British Cohort Study, we investigate the role of maternal gender role attitudes in explaining the differential educational expectations mothers have for their daughters and sons, and consequently their children's later educational outcomes and labour supply. We find that mothers' and children's gender role attitudes, measured some 25 years apart, are significantly correlated, equally so for sons and daughters. Moreover, daughters are significantly more likely to continue school beyond the minimum school-leaving age, participate in the labour force, and work more hours, if their mothers held non-traditional (pro-gender-equality) beliefs, even if they were not working themselves. Consistent with the hypothesis that maternal gender role attitudes affect daughters' economic opportunities only, we find no effect on sons' education outcomes and labour supply. However, we find that mothers' attitudes are significantly correlated with sons' partners' (daughter-in-law) labour supply. All these results suggest that the intergenerational transmission of non-traditional attitudes from mothers to their children explain a substantive part of gender inequalities in economic opportunities, and that attitudes and outcomes persevere across generations through assortative mating.