A social role is a special position an individual possesses within a network, which indicates his or her behaviors, expectations, and responsibilities. Identifying roles of individuals in a social network has various direct applications, such as detecting influential members, trustworthy people, idea innovators, etc. Roles can also be used for further analyses of the network, e.g., community detection, temporal event prediction, and summarization. In this paper, we propose a structural social role mining framework, which is built to identify roles, study their changes, and analyze their impacts on the underlying social network. We define fundamental roles in a social network (namely leader, outermost, mediator, and outsider), and then propose methodologies to identify them, and track their changes. To identify these roles, we leverage the traditional social network analyses and metrics, as well as proposing new measures, including community-based variants for the betweenness centrality. Our results indicate how changes in structural roles, in combination with changes in community structure of a network, can provide additional clues into the dynamics of a network.