a demographic group) and a "bridging" type (which unites people from different groups). He then asked: "Why is US social capital eroding?" and discussed several possible causes. He believed that the "movement of women into the workforce" and other demographic changes had an impact on the number of individuals engaging in civic associations. He also discussed the "re-potting hypothesis", that people become less engaged when they frequently move towns, but found that Americans actually moved towns less frequently than in previous decades. He did suggest that suburbanization, economics and time pressures had some effect, though he noted that average working hours had shortened. He concluded the main cause was technology "individualizing" people's leisure time via television and the Internet, suspecting that "virtual reality helmets" would carry this further in the future. He estimated that the fall-off in civic engagement after 1965 was 10 percent due to pressure of work and double-career families, 10 percent to suburbanization, commuting, and urban sprawl, 25 percent to the expansion of electronic entertainment (especially television), and 50 percent to generational change (although he estimated that the effects of television and generational change overlapped by 10 to 15 percent). 15 to 20 percent remained unexplained. Putnam suggested closer studies of which forms of associations could create the greatest social capital, and how various aspects of technology, changes in social equality, and public policy affect social capital. He closed by emphasizing the importance of discovering how the United States could reverse the trend of social capital decay. Reception A review in Kirkus Reviews praised the book for being understandable for non-academic readers, and said that overall it was an "exhaustive and carefully argued study." The Economist called it "a prodigious achievement." C. S. Fischer, a sociology professor from the University of California, gave a positive review. Although he criticized a few of Putnam's interpretations of the data and felt that "social capital" was an awkward metaphor, he nevertheless called it "a 10-pin strike, a major contribution to study of social networks and social cohesion" with particular praise for its wide use of data. Everett Carll Ladd claimed that Putnam completely ignored existing field studies, most notably the landmark sociological Middletown studies, which during the 1920s raised the same concerns he does today, except the technology being attacked as promoting isolation was radio instead of television and video games. Other critics questioned Putnam's major finding—that civic participation has