The article synthesizes ideas from the capability approach, the embeddedness approach, and Nancy Fraser's three-dimensional scale of justice and develops a theoretical framework for understanding subjective well-being (SWB) as a positive functioning. It also proposes an instrument for measuring SWB and its relationship with participation in non-formal adult education. Using data from the European Social Survey, carried out in 2012, for 24 European countries and applying multilevel linear models for the analysis, the study finds evidence for a positive association between participation in non-formal adult education and SWB. The results show that differences in the SWB among people who have participated in non-formal adult education and those who have not are higher for those who have no higher education and are unemployed than for those who have higher education and paid work. This study also reveals that when people live in countries with better economic and democratic development and a more individualistic culture, the differences in their SWB by participating in non-formal adult education are smaller than when they live in countries with worse economic and democratic development and a more collectivistic culture.