Published by Princeton University Press, the book's central thesis is that social capital is key to high institutional performance and the maintenance of democracy.

The authors studied the performance of the twenty regional Italian governments since 1970, which were similar institutions but differed in their social, economic and cultural context.

They found that regional government performed best, holding other factors constant, where there were strong traditions of civic engagement.

Southern Italy, however, was very different from its Northern-Central counterpart; a group of Norman Mercenaries created order in the area.

Putnam believes that for democracy to be successful there needs to be a level of mutual trust among the citizens and a more horizontal system of governing, all of which Northern and Central Italy has enjoyed.