Background: Informal, unpaid, and lifelong older caregivers of adults with intellectual disabilities (ID) are usually female and most often are mothers of adults with ID. However, research exploring different predictors of subjective and objective burden among these older female caregivers is sparse. The objective of this study was to examine whether the subjective and objective burden as well as positive appraisals are predicted by the same or different variables linked to the caregivers and the adults with ID. Methods: Face-to-face interview questionnaires were administered in a city in Taiwan in 2006-2007 and 350 female family caregivers aged 55 years and older completed the interview in their homes. The independent variables included adult care demands and caregiver variables, while the dependent variables were caregivers' subjective burden, caregivers' objective burden and caregivers' positive appraisals. Results: The results demonstrated that adult care demands were associated more with the objective than the subjective caregiving burden. The strongest predictors of both subjective and objective burden were the care recipient's instrumental activities of daily living functionality, caregiver's age, and caregiver's health status. The significant predictors for positive caregiving appraisals were the caregiver's age and the caregiver's level of social support. Conclusions: The results indicate that both the subjective and objective burdens were mostly related to the same factors, that is, to the characteristics of the older female caregivers and the recipients of care with ID. On the other hand, positive attitudes towards caregiving roles were only associated with caregiver variables.