Parents' educational attainment is one of the strongest predictors of children's cognitive development, which in turn exerts a pivotal influence on children's educational outcomes. However, no prior study has explored change and stability in the relative association of mothers' and fathers' education with children's intelligence (IQ) that may occur across generations. Here, we identified 5 population cohort studies with children born in 1946, 1958, 1970, 1994–1996, and 2000-2002 that were representative of the UK's population at their inception, and that assessed parents' educational attainment and children's IQ (total N in analyses = 48,175). Associations of mothers' and fathers' education with children's IQ ranged from r = 0.38 (CI 95% 0.36–0.41) to r = 0.19 (CI 95% 0.17–0.20) across generations. Fathers' education was more strongly related to children's IQ in the earlier cohorts but in later years, mothers' education emerged as more dominant. However, these differences in the strength of the associations were small and might be chance findings. Negative interactions between mothers' and fathers' education in the prediction of children's intelligence that may reflect compensatory effects were observed in all cohorts, but only reached significance before 1970. We conclude that parents' educational attainment has been continuously associated with children's intelligence across generations with medium to large effect sizes. While our results are based on analyses of large population cohort studies that span across six decades, the limitations of the data and study design warrant a cautious interpretation of our findings.Preregistration & data:https://osf.io/ep3jz/