Pre-print, Working paper: We here use UK data and exploit the State Pension eligibility age to establish the causal effect of parental retirement on adult children's well-being in a Fuzzy Regression Discontinuity Design analysis. Maternal retirement increases adult children's life and income satisfaction by 0.20 standard deviations in the short run. These impacts are stronger for adult children with lower incomes, with young children of their own, and who live close to their retired parents. We emphasise the critical role of intergenerational time transfers from retired mothers in enhancing their adult children's well-being.