Despite the huge prospects of pervasive social computing and the extensive work in context-aware applications, so far very limited work has focused on socially-aware applications. The key requirements to develop such applications are modeling, managing and reasoning about users' social contexts. To fulfil these requirements, in this PhD research, we have made an attempt to model, manage and reason about social contexts to aid the development of socially-aware applications. We study different types of social contexts, their use in various socially-aware applications and possible sources to acquire such social contexts. We will investigate existing context modeling and reasoning techniques and will propose an approach to modeling and reasoning about different types of social contexts. To aid the development of socially aware applications, we will provide a middleware platform for managing the acquisition, changes and provision of social contexts.