The purpose of this study was to investigate the effects of cooperative math activities and individual math activities on children s mathematical problem solving skills, prosocial behaviors, and learning behaviors. For this purpose, 40 children who attended B kindergarten in Seoul city were selected as experimental group (20 children) and comparative group (20 children). For both groups, 12 math activities were conducted, related to the six themes of classification, pattern, number concept, measurement, figure and statistics. Collaborative math activities were conducted in small groups of 4-5 students in the experimental group and individual math activities were conducted one-on-one with the teacher in the comparative group. The pre-test and post-test were performed in both groups with math problem solving skill test, prosocial behavior test, and learning behavior test. The covariance analysis (ANCOVA) was conducted to examine the difference in the effect of the two math activities. The results of this study showed that collaborative math activities had a positive effect on mathematical problem solving skills, prosocial behaviors, and learning behaviors, compared to those of individual math activities. These results signify the educational value of collaborative math activities. This study provides the specific guides and methods to apply collaborative activities in early childhood education environments.