Synopsis: What is the impact of newer information and communication technologies on social capital? In particular, does online participation serve to widen social contacts and expand bridging social capital or to reinforce homogeneous networks? To examine this issue, Part I sets out the theoretical framework, drawing upon Putnam’s theory and the distinction between the role of ‘bridging’ and ‘bonding’ groups. Part II analyzes some of the evidence available from the United States, using the Pew surveys The Internet and American Life, conducted in 2001 to explore online communities. The study finds that online participation has the capacity to deepen linkages among those sharing similar beliefs, as well as serving as a virtual community that spans some generational divisions. Part III briefly speculates about whether we can generalize from this American evidence to other post-industrial societies, notably the Japanese case. The conclusion summarizes the key findings and considers their broader implications for the role of new technologies on social capital.