This study examined the proportion of cooperative play in 4-year-old children across centers (housekeeping, block, manipulative, and computer) and gender in a natural classroom setting. Eighty-four white, middle-income children (41 boys and 43 girls, mean age = 55 months) were videotaped during free-play for 30 minutes per day for four weeks in four activity centers: housekeeping, block, manipulative, and computer. Analysis of Variance revealed that gender had no significant effect on the proportion of cooperative play; however, center was significantly associated with the proportion of cooperative play. Both boys and girls were just as cooperative in the computer center as in block and housekeeping centers and were more cooperative in the computer center than in the manipulative center.