Guided by Orem's theory, this study examined the influence of social environmental factors on rehospitalization among home health care patients. Living arrangement, frequency of caregiving, and type of primary informal care were found to be related to functional ability. Measurable differences in clinical status and functional ability were related to the duration that patients received home health care services until rehospitalization, with the likelihood of rehospitalization increasing proportionately to the magnitude of the differences. Social environmental factors contributed to rehospitalization (self-care deficit) through functional ability (self-care agency) by altering the balance between self-care demand (clinical status) and self-care agency.