The number of mobile phone subscriptions worldwide reached almost 7 billion in 2013. Therefore, the social and psychological consequences of the technology are of great interest to new media scholars and policy makers. Adopting an affordance-based approach, this study examines how different uses of the mobile phone are related to individuals’ subjective well-being and social capital. Findings from a national survey showed that both voice and online communication with the mobile phone is positively related to various indicators of subjective well-being and bonding and bridging capital. Moreover, both bonding and bridging capital mediated the relationship between mobile phone use and subjective well-being. On the other hand, non-communicative uses, such as information seeking activities, were negatively related to positive affect and passing time activities were positively related to negative affect. Implications of the findings are discussed.