Mobile data service (MDS) is any service other than voice calling on a mobile phone. It offers an unprecedented means of connectivity to information and interaction with others, and thus shows great potential in enhancing social capital. This paper proposes a conceptual model to examine the role of MDS in social capital building. By introducing the concept of “degree of mobility obtainable by using MDS over time”, it is expected that this model will be able to explain how and why information and communication technology (ICT) in general and MDS in particular changes individuals’ social capital.