Research from the United States has shown significant increases in the prevalence of three-generation households and in households consisting solely of grandparents and grandchildren. Such shifts in household composition, which are associated with socio-economic disadvantage, may reflect the activation of grandparents as a latent network of support in response to social and demographic changes such as rising partnership disruption. However, to date, little is known in Europe about trends in grandparent households or whether these households are also likely to be disadvantaged. Moreover, we know little about how the familistic and defamilised policy environments in Europe may affect the activation of such latent kin networks. Employing the Integrated Public Use Microdata Series—International and the Office for National Statistics’ Longitudinal Study for England and Wales, we used multivariate techniques to investigate changes in prevalence over time in co-residence with a grandchild across Austria, England and Wales, France, Greece, Portugal, Romania, and the United States. We expected increases in grandparent households in Portugal and Greece, familistic societies with few public alternatives to family support. However, only Romania (like the US) showed an increase in the percentage of people aged 40 and over co-residing with their grandchildren in three-generation households between the late 1970s and 2002. Given rises in poverty and limited support for low-income families in Romania, rises in grandparent coresidence may reflect a coping strategy among poorer families to increasing financial hardship. Regardless of the trends, grandparent households in all the countries studied remained associated with socio-economic disadvantage.