Type A behaviors were observed in a group of 48 preschool children in different free-play and competitive situations. Interrater reliability was assessed on the Matthews Youth Test for Health (MYTH), and the children's and their parents' type A scores were compared. Scores on the MYTH were used to classify children as either type A or type B. Comparisons were made between type A and type B children's play in classroom and in laboratory situations. For the laboratory situations, 24 same-sex type A-type B dyads were formed, and the dyads were observed in free play, followed by car racing, by a tower-building contest, and by an interview. Type A children more frequently showed annoyed facial expressions, gross motor activity, interruptions during classroom free play, and gross motor activity and aggressive play with an inflatable Bobo doll during the laboratory free-play situation. Type A children more often won the car race and the tower-building contest, and they answered a greater number of questions and more frequently answered first during the interviews. These data are consistent with other findings on type A behavior in preschool children and suggest that the behavioral dimensions of type A (competitiveness and impatience-aggression) may emerge as early as the preschool years, particularly in competitive situations.