The purpose of this study was to explore the relationship of selected prosocial play behaviors in children to moral reasoning, participation in youth sports, and perception of sportsmanship. A prosocial play behavior inventory which utilized teachers' observations of children was developed by the investigator and 16 elementary school teachers. This inventory was used to assess the prosocial play behavior of the children studied. A reliability coefficient of r = .98 was obtained for the inventory using the split-half method for estimating the internal consistency of a test. Assessment of the children's moral reasoning followed the method described by Kohlberg et al. (1976)