This cross-sectional study attempted to (1) demonstrate that children's sex role orientation is related to their tendency for Type A behavior and (2) ascertain whether children expressing Type A behavior would experience difficulty in making and keeping friends. Participants were 286 kindergarten children and elementary school students in the first four grades attending one private and one public school. Each child was interviewed separately to obtain self-ratings on a sex role questionnaire, responses to a Type A questionnaire, and nominations of peers' sociometric status. Teachers rated children on sex role and Type A behavior. Findings indicated that the masculine sex role is associated with Type A behavior. Several results suggested the possibility of a developmental trend from kindergarten to fourth grade in the expression of Type A behavior by certain sex role groups. Aggressive Type A behavior was associated with masculinity, and with the absence of masculinity and femininity (i.e., the undifferentiated individual). The MYTH test of children's Type A behavior was found to contain items measuring two factors: one measuring leadership and competitiveness, the other measuring aggressiveness and impatience. It is concluded that the data strongly suggest that Type A behavior in early grade school children is predictive of the quality of peer relationships. Hostile Type A children make poor friends. (RH)