[1] The book is an influential analysis of the bases of democracy across the world.

Larry Diamond and Gary Marks argue that "Lipset's assertion of a direct relationship between economic development and democracy has been subjected to extensive empirical examination, both quantitative and qualitative, in the past 30 years.

And the evidence shows, with striking clarity and consistency, a strong causal relationship between economic development and democracy.

"[2] In Chapter V, Lipset analyzed "Fascism"—Left, Right, and Center, and explained that the study of the social bases of different modern mass movements suggests that each major social stratum has both democratic and extremist political expressions.

The book sold more than 400,000 copies and was translated into 20 languages, including: Vietnamese, Bengali, and Serbo-Croatian.