Using a Japanese national-sample panel survey in 2000 that includes snowball-sampled data, this paper attempts to examine the extended hypotheses on social capital. One focus of the extension is on the role of social networks, a low-cost device for obtaining political information that also operates as a portal to the society. The other focus includes the role of tolerance, which is as important as political participation in an open democracy. By positing a hypothesis that the reverse logic of social capital is applicable to the problem of intolerance, an attempt is made to elucidate the dark side of social capital. The result of multivariate analyses clearly indicates a positive correlation between social capital and political participation, both of voluntary organization and social networks, on the individual and the dyadic levels. On the other hand, political tolerance is not clearly related with social capital at any level.