The development of social interaction was studied in infant coyotes, beagles, and wolves. In this paper, social play behavior is discussed. Social play may be characterized in a number of ways: (i) actions from various contexts are incorporated into labile (unpredictable) temporal sequences; (ii) the "play bout" is typically preceded by a metacommunicative signal which indicates "what follows is play"; these signals are also observed during the bout; (iii) certain actions may be repeated and performed in an exaggerated manner; (iv) the activity appears "pleasurable" to the players.
By comparing these three species, some insight into the dynamics of social play may be gained. Coyotes were the least successful in soliciting play. When they did play, 90% of all bouts had been previously solicited. Coyotes also tended to use the most successful signals most frequently. This trend was not observed in the beagles or the wolves. By taking into account the fact that infant coyotes are significantly more aggressive than either infant wolves or beagles, the differential ontogeny of social play can be explained. Some of the functions of social play in canids are discussed, and it is concluded that social play is a valid class of social behavior and lends itself nicely to quantitative study.