An opening section on basic processes provides a general background on the mechanisms involved in play and provides a foundation for the rest of the book. The section on atypical populations focuses on parent-child play among clinical populations, including Down syndrome children, premature children, hyperactive children, and economically distressed families and families with depressed parents. It expands the context of the populations' data described in the first section and provides some additional insight into mechanisms. Finally, the book describes some of the enormous cross-cultural variations in play behavior.