Subjective well-being (SWB) is often described as being U-shaped over adulthood, declining to a midlife slump and then improving thereafter. Improved SWB in later adulthood has been considered a paradox given age-related declines in health and social losses. While SWB has mostly been studied in high-income countries, it remains largely unexplored in rural subsistence populations lacking formal institutions that reliably promote social welfare. Here, we evaluate the age profile of SWB among three small-scale subsistence societies (n = 468; study 1), forest users from 23 low-income countries (n = 6987; study 2), and Tsimane horticulturalists (n = 1872; study 3). Across multiple specifications, we find variability in SWB age profiles. In some cases, we find no age-related differences in SWB or even inverted U-shapes. Adjusting for confounders reduces observed age effects. Our findings highlight variability in average well-being trajectories over the life course. Ensuring successful aging will require a greater focus on cultural and socioecological determinants of individual trajectories.