This research uses a life course perspective's emphasis on linked lives and the life-long course of development to posit that adult children's problems create stressful concerns in the lives of older parents in a process of intergenerational stress proliferation. We link these concepts with issues of timing by examining the importance of parents’ basic physical limitations for the process of intergenerational stress proliferation. A longitudinal study of older adults shows that children's problems are related to increases in parental concerns, but effects are diminished for mothers when they experience relatively high levels of physical limitations.