In 2000, political scientist Robert Putnam published a massive book, Bowling Alone: The Collapse and Revival of American Community, which became that rarest of things: an intellectually meaty bestseller.

Putnam, it turned out, was in the right place at the right time. Across the ideological spectrum, Americans have become increasingly troubled by a decline in community. The remedy? "Social capital," referring to the cumulative clout of "social networks, norms of reciprocity, mutual assistance, and trustworthiness." It is the glue that helps people achieve concrete goals while at the same time benefiting others who may not be directly involved. For example, crime tends to be lower where there are strong neighborhood associations, benefiting residents who are not active in community organizing as well as those who are.

Hence Putnam's latest project, Better Together, a collaboration with Lewis Feldstein, president of the New Hampshire Charitable Foundation, and Don Cohen, "who did much of the field research and most of the actual writing of the case studies" that make up the book.

These 12 case studies range widely across the United States, offering examples of very different enterprises, from the Harvard Union of Clerical and Technical Workers to Rick Warren's Saddleback Church in Lake Forest, California; from branch libraries in Chicago to a far-sighted strategy for local business growth in Tupelo, Mississippi. Each example is intended to show in a practical way what is involved in "creating social capital: developing networks of relationships that weave individuals into groups and communities."

Taken together, they "suggest that social capital is usually developed in pursuit of a particular goal or set of goals and not for its ...