I examined the relation between household parameters of size, composition, and temporal variability and indicators of care-giver and elder well-being. Two discrete groups of 20 care-giver-elder pairs were included in the study: (a) a group in which elders were moderately to severely cognitively impaired, but physically well, and (b) a group in which elders were moderately to severely physically disabled, but cognitively unimpaired. Care givers and elders were interviewed and assessed in their homes, and the care giver completed a 3-day log of home-care activities. Results indicated that care-giver and elder well-being are related to opposite values of the same household parameters in the two groups. The study demonstrates the utility of a social-ecological framework for research on home care, and suggests that the degree of fit of any particular household arrangement is relative to the competence-disability profile of the elder in care.