1. Introduction; 2. The evolutionary origins of play revisited: lessons from turtles G. M. Burghardt; 3. Play in common ravens (Corvus corax) B. Heinrich and R. Smolker; 4. Object play by adult animals B. Heinrich and R. Smolker; 5. Kangaroos at play: play behaviour in the Macropodoidea D. M. Watson; 6. Intentional communication and social play: how and why animals negotiate and agree to play M. Bekoff and C. Allen; 7. The structure-function interface in the analysis of play fighting S. M. Pellis and V. C. Pellis; 8. Sparring as play in young pronghorn males M. N. Miller and J. A. Byers; 9. Squirrel monkey playfighting: making the case for a cognitive training hypothesis M. Biben; 10. Self assessment in juvenile play K. V. Thompson; 11. Biological effects of locomotor play: getting into shape, or something more specific? J. A. Byers; 12. Neurobiological substrates of play behaviour: glimpses into the structure and function of mammalian playfulness S. M. Siviy; 13. Play as an organizing principle: clinical evidence and personal observations S. Brown.

' … anyone interested in play should not hesitate to read or buy this book. It puts down a definite marker for play research in the 1990s, and suggests many interesting leads for research on play through into the next millenium.' Peter K. Smith, Animal Behaviour