This quasi-experimental study used nonrandomized control group pretest posttest design, aiming to find out whether cooperative learning techniques numbered heads together effectively improved social skills in kindergarten students. The result of statistical test by using mann whitney and wilcoxon test showed significant 0,005 (<0,05) indicating that there is difference of social skill in research subject before and after implementation. This suggests that cooperative learning techniques numbered heads together effectively improve the social skills of kindergarten students both on aspects of communication, cooperation, assertiveness, responsibility, empathy, self-involvement and self-control.