Purpose: This qualitative study aimed to understand older adults' perspectives on successful aging and develop a model of a successful aging process, within the Korean socio-cultural context. Methods: This study used a Grounded Theory approach. Through theoretical sampling, 14 participants were selected from older adults at a public health center and a volunteer institution in Gyeonggi Province, South Korea. Results: The basic social process identified was "expanding the aging self", which was preceded by three phases, namely, adjusting to the changes, developing the valuable self, and embracing the environment. Participants used 2-3 strategies for successful aging in each phase. For adjusting to the changes, participants used strategies such as "adopting a positive attitude", "accepting the changes", and "being at the center of life". To develop the valuable self, "re-identifying capacities", "having something to do", and "advancing to a healthy lifestyle" were used. Participants embraced their environments with "sharing with others" and "embracing younger generations". The causal condition for expanding the aging self was the changes in participants' physical, mental, or psychosocial situations. Conclusion: These findings suggest a theoretical foundation for the development of potential nursing interventions to promote self-care management and the interpersonal relationship for successful aging among Korean elderly individuals.