Social conformity surrounds and enmeshes us, but we are seldom aware of its full impact. This book demonstrates just how pervasively social conformity affects society and politics. The impact of conformity on voting behavior and government is a particular focus. When conformity affects voters' choices, it runs contrary to the idea that they are making a rational decision among political parties or candidates-the basis of democracy-and it can lead to unexpected political consequences. At the extreme, social conformity can hijack democratic government and lead to violence against minority groups or totalitarianism. The impact of conformity is assessed through quantitative and qualitative analyses, a few simple mathematical models, and specific numerical predictions that are verified with historical data from the USA, Germany, Japan, Russia, and many other countries over much of the 20th century. The results give new insights on voting, political party systems, crime, ethnic violence, democratic government, and the nature of society, including both positive and negative consequences of conformity. Building on research in cognitive psychology over the last twenty years, the book also ties conformity and resulting social institutions to certain cognitive processes that go on without a person's conscious awareness.