Users are burdened with the task of configuring access control policies on many different application platforms used by mobile devices and social network sites. Many of these platforms employ access control mechanisms to configure application permissions before the application is first used and provide an all or nothing decision for the user. When application platforms provide fine grained control over decision making, many users exhibit behavior that indicates they desire more control over their application permissions. However, users who desire control over application permissions still struggle to properly configure them because they lack the context in which to make better decisions. In this dissertation, I attempt to address these problems by exploring decision making during the context of using mobile and social network applications. I hypothesize that users are able to better configure access control permissions as they interact with applications by supplying more contextual information than is available when the application is being installed. I also explore how logged access data generated by the application platform can provide users with more understanding of when their data is accessed. Finally, I examine the effects that this contextually improved application platform has on user decision making.