Summer is a time of reduced physical activity (PA) for children; however, summer care programs (SCPs) can provide opportunities for children to be active and foster friendships. This study investigated associations between PA and friendship formation at SCPs. Children (ages 8-12 years) from two SCPs reported demographics, PA, and up to five friends at the program. Exponential random graph modeling determined significant factors associated with connections at each time point and between time points. PA was a significant factor in sending and maintaining friendship connections. A further understanding of the social dynamics which assist in the maintenance of PA behaviors during summer may improve the odds children engage in the recommended amounts of PA during this crucial time.