Discovering whether social capital endowments in modern societies have been subjected or not to a process of gradual erosion is one of the most debated topics in recent economic literature. Inaugurated by Putnam’s pioneering studies, the debate on social capital trends has been recently revived by Stevenson and Wolfers (2008) contending Easterlin’s assessment. Present work is aimed at finding evidence for the relationship between changes in social capital and subjective well-being in western Europe, Australia, Canada and Japan between 1980 and 2005. In particular, I would like to answer questions such as: (1) is social capital in western Europe, Canada, Australia and Japan declining? Is such erosion a general trend of modern and richer societies or is it a characteristic feature of the American one? (2) can social capital trend help explain subjective well-being trend? Therefore, present research considers three different set of proxies of social capital controlling for time and socio-demographic aspects using WVS-EVS data between 1980 and 2005. Present results are encouraging, showing evidence of positive correlation between several proxies of social capital and both happiness and life satisfaction. Furthermore, results show that during last twenty-five years people in some of the most modern and developed countries have persistently lost confidence in the judicial system, religious institutions, parliament and civil service.