This study aimed to determine the effect of optimizing the understanding of handball game material on students' social interaction skills. The method used in this research is the ex post facto descriptive method. The results of the study: 1) Handball learning had a significant effect on the social interaction skills of students who took the handball course in the Undergraduate Penjaskesrek Study Program, FOK Ganesha University of Education. (2) The social interaction ability of students who take the handball course is included in the good category. The individual is 75% while the group is 71%. (3) The results of observations also show that the social interaction skills of students who take handball courses are in a good category, which is 69.87%. In conclusion, handball learning has a positive and significant effect on the social interaction skills of students who take handball courses at the Undergraduate Penjaskesrek Study Program,