Social games have become popular on social media such as Facebook and MySpace. While there are plenty of market reports regarding social media, the related academic research is limited. This study applies Homans’ cost‐reward structure from Social Exchange Theory to investigate how social games change people’s social behavior on social media. The concepts of rewards are drawn from the gratifications of social media use, and the concepts of costs are drawn form the symptoms of media addiction. In a survey of 323 college students, participants’ perceived rewards and costs of Facebook use and game play are measured. The results indicate social game players perceived significantly higher costs of Facebook use than non‐players. In addition, costs of Facebook use and costs of game play also play important roles to influence social game players’ willingness to play more social games. Discussion and limitations are provided. / text