A study on the effect of viewing violence on television on childrens' behavior was conducted within the context of sport activity. Three sports--baseball, hockey, and lacrosse--were chosen. Teams of children from three different age groups were the subjects. Within each of the age levels in each sport, teams were selected and assigned to prosocial, antisocial, and control treatment conditions. Experimental television inputs were selected from available recordings of actual athletic events and edited to be relatively antisocial, prosocial, or neutral for the appropriate treatment groups. Observations of players' behavior included measures of physical, verbal, and nonverbal symbolic aggression, and prosocial behavior. The most notable finding was that exposure to prosocial media presentations appeared to consistently reinforce prosocial behavior on the part of the subjects. It is concluded that relationships that may exist between media aggression and viewer's aggression were not detected. Mean values for age and treatment conditions in each sport are presented in tabular form. (JD)