Cooperation and competition are both essential elements of economic life. Here we explore how cooperativeness in a prisoner’s dilemma is correlated with competitiveness in a sample of 9-12-year-old children in Colombia and Sweden. Using two different measures and four different tasks for competitiveness, we find no consistent relationship between cooperativeness and competitiveness. However, we find evidence of a negative relationship between willingness to compete in a math task and cooperativeness in the overall sample. Competitiveness in math has previously been related to educational choices and may therefore be the most economically relevant relationship.