Background and Objectives: This study investigates whether the association between supplementary grandchild care and grandparents' subjective well-being-measured as life satisfaction, perceived stress, and loneliness-is moderated by the contextual environment. We use the coronavirus disease (COVID-19) pandemic as an example of contextual differences. Drawing on role theory, we argue that the costs and benefits of grandparenting may have differed between pandemic and prepandemic times. On the one hand, providing grandchild care during the pandemic may have been particularly stressful, prompting more negative effects on well-being. On the other hand, grandchild care may have been particularly relevant for enhancing well-being, as it protected grandparents from social isolation. Moreover, the association between grandparenting and well-being may have differed by gender., Research Design and Methods: Using unbalanced panel data from the German Ageing Survey (DEAS) 2014 ( n = 3,619), 2017 ( n = 2,458), and 2020 ( n = 2,021), we applied maximum likelihood structural equation modeling (ML-SEM) - a method that combines dynamic panel modeling with fixed-effects analysis - to examine whether there were differences in the relationship between grandchild care and grandparents' well-being when comparing pandemic and prepandemic times and by grandparents' gender., Results: Grandchild care was associated with lower loneliness for both grandmothers and grandfathers. For grandfathers, this association was even stronger during the pandemic. Grandmothers experienced higher life satisfaction when taking care of grandchildren during the pandemic, but there was no evidence that grandchild care increased perceived stress for either grandmothers or grandfathers., Discussion and Implications: In line with role enhancement theory, this study highlights that supplementary grandchild care can be beneficial for grandparents' well-being. Moreover, the context in which grandchild care takes place shapes the costs and rewards associated with it. Our results suggest that supportive policies and programs facilitating grandchild care can enhance grandparents' well-being, especially in challenging contexts., Competing Interests: None., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Gerontological Society of America.)