Based on a 3-year observational study of children at play in a variety of settings, this book is a description of the play behavior of preschool children. In Section I, "Playing with Ideas," the chapters are: (1) "Questions about the World"; (2) "What Is, What Was, and What Will Be"; and (3) "Questions about Life." In Section II, "Active Play" chapters are: (1) "Exercise Play"; (2) "Game Play"; and (3) "Trying Out New Sports." In Section III, "The Scientist at Work," chapters are: (1) "Investigations"; (2) "Transformations"; and (3) "The Naturalist." Chapters in Section IV, "Playing School," are: (1) "Word Play"; (2) "Story Telling"; and (3) "Numbers." In Section V, "Playing with Friends," chapters are: (1) "Imaginary and Invisible Friends"; (2) "Intimate Friends"; and (3)"Playing with a Group." In Section VI, "Ways of Playing," chapters are: (1) "Play Acting"; (2) "Creative Play"; and "Play Choices." At the end of each chapter, suggestions for parents and play ideas are given. (LPP)