Grandparental child care is an important form of intergenerational support. Thisarticle explored first time whether the transition to retirement affects the amount of grandchildcare that European grandparents provide to their descendants. The association between entryinto retirement and grandchild care was studied using the longitudinal Survey of Health,Ageing and Retirement in Europe conducted in 16 countries and four regimes: SouthernEurope, Central Europe, Northern Europe, and Eastern Europe. Data collected in five wavesbetween 2004 and 2015 were utilized. We ran panel fixed-effect regression models, whichconsider individual’s variation and person-specific changes over time, providing a test forcausality in the associations between retirement and grandchild care. Transition to retirementwas associated with increased grandchild care among both grandmothers and grandfathers.Grandmothers more often looked after grandchildren than grandfathers, but entry intoretirement increased grandchild care more among grandfathers than grandmothers. Transitionto retirement was associated with increased grandchild care in all parts of Europe, but themagnitude of the effect was strongest in Southern Europe, followed by Northern Europe,Central Europe, and Eastern Europe, respectively. This study indicated that when the roleconflict as grandchild caregivers and employees disappears, the amount of grandchild careolder Europeans provide to their descendants increased. The fact that at retirement older adultshave more time resources to provide informal family support should be carefully acknowledgein policymaking and discussions considering the societal role of older people.