This study of the behavior of a mixed group of male and female preschoolers in an indoor, free-play setting was designed to clarify two general issues: (1) the ratio of aggressive to non-aggressive disputes and the factors in the situation which may be associated with this relationship; and (2) the factors in the conflict episodes themselves which may be related to whether a participant wins or loses a dispute. Study subjects were five boys and five girls, aged 3-5 years, randomly selected from each of two groups of preschoolers. Each focal child was fitted with a wireless microphone and a continuous video-tape was made of the child's behavior, together with the behavior of all the children with whom the child interacted during a single 3-hour free-play session. The tapes were viewed to identify conflict episodes over territory, property, and interpersonal control. Any exhibition of aggressive behavior in conflict episodes was also noted. Results indicated that in a free-play setting with an equal number of boys and girls, the absolute number of aggressive conflicts did not vary significantly, but there were more non-aggressive conflicts between girl dyads and mixed pairs than between boy pairs. Territory disputes were found to be more aggression prone than either interpersonal control or possession disputes. There was no indication that the use of aggressive behavior, in and of itself, improved the preschooler's chance of winning a conflict. (CM)