Recent studies have argued that grandparents have a direct effect on grandchildren's achievements, net of parental resources. However, little is known about the underlying mechanisms. One explanation is that grandchildren can benefit from the cultural resources that grandparents transmit to their grandchildren. If this is the case, one would expect strong effects in families where grandparents are highly involved in the lives of their grandchildren and weak or no effects in other families. Using new nationally representative survey data on three generations in the Netherlands, we examine if and how grandchildren's educational attainment is affected by three grandparental resources: education, occupational status, and cultural resources. We explore how these effects vary by the strength of the tie between grandparent and grandchild. We find no evidence for a main direct grandparental effect, nor do we find interactions with the strength of the tie between grandparent and grandchild. These null-findings are discussed in light of the mixed body of evidence that has been accumulated in the literature and contemporary theorizing on grandparenting.