The aim of this study was to develop and validate an assessment tool for research consent competence in older participants. A four-item instrument was developed to assess the capacity of the older adults to consent to research. Data were obtained from 203 nursing home residents from two facilities and 201 community-dwelling older adults in a metropolitan city in South Korea. The results revealed that the four-item instrument for assessing the capacity of older adults to consent to research had good internal consistency, convergent and concurrent validity, an acceptable model fit, and good sensitivity and specificity. The short form can be used for gerontological researchers to encourage their older participants to have the capacity to consent to research in informed consent process. (Contains 4 tables.)