We investigated the conditions under which married children live with their older parents in Japan. We focused on how needs and resources in each generation are associated with whether married couples live with their parents in parent-headed and child-headed households, and we also investigated difference in power relations between older and younger generations and between children and their spouses. We analyzed a nationally representative sample of older parents (n = 3,853) and their married children (n = 8,601) from the 1999 Nihon University Japanese Longitudinal Study of Aging (NUJLSOA). Mutinomial regression revealed that married children with relatively affluent parents tended to live with them in parent-headed households and that married children with parents who are in relatively poor health or who are widowed tended to live with them in child-headed households. We also found that less-educated married children tended to live in the households of their higher-income parents, suggesting that parents may be “purchasing” traditional arrangements with less-affluent children. In addition, children with an educational advantage over their spouses were more likely to have parents living with them in child-headed coresident households. We conclude that traditional multigenerational coresidence has become a commodity negotiated within families based on relative resources and needs within and across generations