This study addressed an issue of current community concern about which there is little relevant research, namely the behavioural effects of viewing an aggressive cartoon and playing with the toys associated with it, in comparison to a neutral cartoon and toys. Sixty preschool children were observed in groups of five after viewing either an aggressive cartoon, a neutral cartoon, or no cartoon, when playing with each type of toy in turn. Levels of aggression were considerably higher when children played with the aggressive toys after watching the aggressive cartoon, than after exposure to the neutral cartoon and toys. The opposite trend occurred for prosocial behaviour. The effects of watching cross-matched cartoons and toys (e.g., aggressive cartoon and neutral toys) were less clear-cut, but still indicated negative effects of both aggressive cartoons and toys. Results are interpreted in terms of a cognitive information-processing model, and the implications for the development of aggression, and for policy decisions on television programming and toy marketing, are explored.