The older population in Thailand is growing, and the number of older people who suffer from health problems is increasing as well. The health situation of the older population challenges healthcare providers to care for older people. Healthy aging is key to promoting the health of older people and sustaining their well-being. However, little is known about healthy aging in Thailand, especially in northeastern Thailand, or the Isan region, where the number of older people is increasing. Thus, this thesis aims to understand the factors associated with perceived health and healthy aging and how older people and their relatives in the Isan region conceptualize healthy aging. This thesis also focuses on how community nurses experience the meaning and promotion of healthy aging in this region. This thesis includes four studies. The first is a quantitative cross-sectional study with 453 participants aged 60 years or older. The second and third studies are qualitative with a phenomenographic approach that is based on lifeworld theory. Participants in the second and third studies include 17 older people and 14 relatives who are responsible for caring for older people, respectively. The fourth study is a qualitative study that involves focus group interviews with 36 community nurses who work with older people in the Isan region. The findings of the first study show a variance (24.3%) in perceived health and healthy aging based on residential area, marital status and disability status. The meaning of healthy aging, which was derived from the second, third and fourth studies, was divided into three domains: being interconnected; being able to do something good and feeling strong; and thinking beyond the capacity and functions of body and mind. The promotion of healthy aging was described as “providing health assessments”, “sharing knowledge”, and “having limited resources”. The findings of the first study revealed the key factors that will help healthcare providers promote healthy aging. The findings of the second, third and fourth studies revealed that older people, their children and grandchildren, and community nurses attach different meanings to healthy aging. The finding regarding promotion of healthy aging emphasizes that the person-centredness should be integrated in practice when promoting healthy aging. The results of this thesis will be useful to policymakers, who can apply this enhanced understanding of healthy aging to develop healthcare practices that promote healthy aging.