Jointly discovering user roles and data clusters using both access and side information by performing the following operation: (i) representing a set of users as respective vectors in a user feature space; representing data as respective vectors in a data feature space; (ii) providing a user-data access matrix, in which each row represents a user's access over the data; and (iii) co-clustering the users and data using the user-data matrix to produce a set of co-clusters.