Purpose: The purposes of this study were to examine the relationships among activities of daily living, self-efficiency, nursing home care quality and nursing home adaptation, and to identify the influencing factors of nursing home adaptation in nursing home residents. Methods: The study employed a descriptive correlational design. The data were collected from 148 older adults without dementia by interview from six nursing homes in three cities from February 1, 2008 to February 28, 2008. Results: Levels of nursing home adaptation in older adult residents were different by type of decision maker of nursing home admission, reason of nursing home admission, type of payment and length of nursing home stay. The nursing home adaptation was significantly correlated with self-efficiency and nursing home care quality. The strongest predictor of nursing home adaptation was type of decision maker of nursing home admission followed by the self-efficiency. Conclusion: The study suggested that during the decision making period of nursing home admission, older adults should have enough time and careful considerations of their families to decide by themselves in positive ways. Nursing home staff should be able to identify reasons of nursing home admission and demands or expectations of older adults and their families.