This study seeks to explain why people place their faith in strangers, and why doing so matters. Trust is a moral value that does not depend on personal experience; we learn to trust from our parents. Trusting societies are more likely to redistribute resources from the rich to the poor, and to have more effective governments. Trust has been in decline in the United States for over 30 years. Uslaner uses aggregate time series and cross-sectional data to show that the roots of this decline can be found in declining optimism and economic inequality.