The aims of this study were: (a) to examine general perceptions of filial obligations toward sharing housing with older parents and stepparents; and (b) to assess the effects of selected contextual factors on those normative beliefs. A national sample of 579 men and 582 women (mean age = 44.6, SD = 17.2) responded to a multiple segment factorial vignette in which an older parent or stepparent was portrayed as needing help with housing. Respondents thought that parents should be helped more than stepparents, younger adults with greater resources were more obligated to help older parents and stepparents than were those with meager resources, and older parents and stepparents with greater need acuity were expected to be helped more than older parents and stepparents with less serious housing needs. Attitudes about co-residence were based on family obligation norms, beliefs about repaying older adults for past help, perceived relationship quality, other demands on the younger adult's resources, the older person's resources, and moral responsibilities to assist. (Contains 3 tables.)