Americans were active in the social and political life of their communities in the first two-thirds of the 20th century, so “Why, beginning in the 1960s and 1970s and accelerating in the 1980s and 1990s, did the fabric of American community life begin to unravel?" (184). In 1960, 41% and 8% of Americans had completed high school and college, respectively, while the corresponding percentages in 1998 were 82% and 24%. Because education is a strong predictor of participation in public organizations, the decline in communal engagement must be attributed to other factors.

Putnam investigates whether the decline in civic engagement is correlated across space and time with social characteristics. He has two concerns with this approach. First, it ignores synergistic effects or those that spread beyond the point of initial contact. For example, if women working outside the home invite fewer people to dinner, ultimately those women who do not work might stop doing so as well. Secondly, there is no social characteristic that stands out to explain this phenomenon. To be sure, participation varies among different social groups, but the downward trend is universal. Assuming the role of sleuth, Putnam considers possible explanations, such as time pressures, the economy, the movement of women into the paid labor force, residential mobility, suburbanization, television, the disruption of marriage, the welfare state, and the civil rights revolution.