As a cultural psychologist, I have been engaged in cross-cultural investigations on happiness and social relationships. Specifically, I am interested in how people achieve subjective well-being and how cultural values affect this process. The evidence I have obtained so far suggests that in Japan, compared with North American or European cultures, the source of happiness is more likely to be connected with social relationships and social capital within a society. Based on these findings, I further investigate how social capital functions within communities.From large social survey studies and fieldwork in agricultural and fishing communities in Japan, my colleagues and I are examining which environmental and cultural effects support happiness in communities at both the individual and the group level. From such investigations, I would like to propose an index of “collective well-being” which can be applied to assess the sustainability of happiness.