Concepts embody our knowledge of the kinds of things there are in the world. Tyingour past experiences to our present interactions with the environment, they enable us to recognizeand understand new objects and events. Concepts are also relevant to understanding domains such associal situations, personality types, and even artistic styles. Yet like other phenomenologicallysimple cognitive processes such as walking or understanding speech, concept formation and use aremaddeningly complex. Research since the 1970s and the decline of the "classicalview" of concepts have greatly illuminated the psychology of concepts. But persistent theoreticaldisputes have sometimes obscured this progress. The Big Book of Concepts goesbeyond those disputes to reveal the advances that have been made, focusing on the major empiricaldiscoveries. By reviewing and evaluating research on diverse topics such as category learning, wordmeaning, conceptual development in infants and children, and the basic level of categorization, thebook develops a much broader range of criteria than is usual for evaluating theories ofconcepts.