The first step in migrating to a role based access control (RBAC) system, is role development, in which teams of people meticulously define sets of roles that meet the needs of an organization's security and business requirements. Because it is so labor intensive, role development is the most expensive step in migrating to RBAC. In this talk, I will describe an approach called role discovery to help assist with the role development process. We attack the problem by finding simplifications of a bipartite graph that models the existing access control rules. Biclique covers of this graph are a fundamental tool in our approach. I will describe some of the theoretical background of this problem as well as some experimental results testing the approach on several real-world datasets.