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. This new stream of research has been inaugurated by Putnam's pioneering studies about social capital trends in the United States. Recently, a considerable work by Stevenson and Wolfers (2008) put a new emphasis on this topic contending Easterlin's assessment. Present work is aimed at analyzing the relationship between changes in social capital and subjective well-being in seven European countries and in Japan between 1980 and 2005. In particular, we would like to answer questions such as: 1) is social capital in Europe and Japan declining? Is such erosion a general trend of modern societies or is it a characteristic feature of the American one? 2) social capital trend can help to explain subjective well-being trend? In so doing, our research considers three different set of proxies of social capital controlling for time and socio-demographic aspects using WVS data between 1980 and 2005. Our results are encouraging, showing evidence of a probable relationship between social capital and happiness. Furthermore, our results show that during last twentyfive years European and Japanese citizens have persistently lost confidence in the judicial system, in the church, in politics and in civil services.