In response to the rapid growth in mass incarceration, a burgeoning literature documents the mostly deleterious consequences of incarceration for individuals and families. But mass incarceration, which has profoundly altered the American kinship system, may also have implications for relationships that span across generations. In this paper, I use data from the Fragile Families and Child Wellbeing Study, a longitudinal data source uniquely situated to understand the collateral consequences of incarceration for families, to examine how paternal incarceration has altered two important aspects of intergenerational relationships: children's co-residence and contact with grandparents. Results show that the association between paternal incarceration and grandparent co-residence results from social selection forces, but that paternal incarceration—especially incarceration lasting three months or longer and incarceration for violent offenses—is associated with less contact with paternal (though not maternal) grandparents. More than one-quarter of this negative relationship is explained by separation between parents that often occurs after paternal incarceration, highlighting the potentially “kinkeeping” role of mothers and the role of fathers in structuring children's relationships with grandparents. Additionally, these negative consequences are strongest among children living with both parents prior to paternal incarceration and among children of previously incarcerated fathers. Taken together, the results provide some of the first evidence that the collateral consequences of incarceration may extend to intergenerational relationships.