The session will begin with a discussion on the different theoretical models of disability, focusing specifically on distinctions between disability definitions within the commonly used ICF primarily employed by disability researchers and some health researchers internationally, and that of functional limitation scales (ADLs, IADLs) regularly used by aging researchers. The ICF model categories health and disability related experiences beyond the concept of disease, and includes both environmental and personal determinants of outcomes, while the ADLs and IADLs focus on functional limitations. The roundtable will discuss both the theoretical and methodological overlaps and distinctions between using the ICF model and the functional limitation scales in research. The discussion will move on to identify differences within the aging population – specifically highlighting distinctions between adults who are aging with disability and those who are aging into disability and how they are counted and evaluated in research. Difficulties with measuring and interpreting time variables, such as age of onset verses chronological age, will be presented and audience discussion encouraged. Finally, this roundtable will focus on successful aging among those who are aging with a disability and those who are aging into disability. Successful aging refers to multidimensional factors that contribute to maintaining good physical and mental health, cognitive functioning and sustained active engagement in social and productive activities in the aging process. These factors may vary across people who are aging with disability and people who are aging into disability. The challenge of measuring successful aging across these two groups will be presented and discussed. This roundtable will be facilitated by SSWR members affiliated with the Special Interest Groups in both Aging and Disabilities and will be structured to encourage active participation by attendees.