One need not look far to find breathtaking acts of stupidity committed by people who are clever, or even brilliant. The behaviour of clever individuals - from presidents to prosecutors to professors - is at times so amazingly stupid as to seem inexplicable. Why do otherwise intelligent people think and behave in ways so stupid that they sometimes destroy their livelihoods or even their lives? This is an investigation of psychological research to see what it can tell us about stupidity in everyday life. The contributors to the volume, scholars in various areas of human intelligence, present examples of people messing up their lives, and they offer insights into the reasons for such behaviour. From a variety of perspectives, the contributors discuss: the nature and theory of stupidity; how stupidity contributes to stupid behaviour; and whether stupidity is measurable. While many millions of dollars are spent each year on intelligence research and testing to determine who has the ability to succeed, next to nothing is spent to determine who will make use of their intelligence and not squander it by behaving stupidly. The contributors focus on the neglected side of this discussion, reviewing the full range of theory and research on stupid behaviour and analyzing what it tells us about how people can avoid stupidity and its devastating consequences.