Unlike many edited ‘greatest hits’ volumes, this book's chapters explore exactly one viewpoint: the fast-and-frugal heuristics research program of the Adaptive Behavior and Cognition (ABC) Research Group at the Max Planck Institute for Human Development in Berlin. The studies emanating from this research program suggest that very simple cognitive heuristics comprise highly accurate inference strategies. These primitive heuristics enable humans to perform cognitive tasks both with great speed and with a truncated information search – hence the name of the research program ‘fast-and-frugal’.