This specification describes technologies relating to identification of interests of a subgroup of a larger group of users. One aspect of the subject matter described in this specification can be embodied in methods that include receiving data reflecting characteristics for users in a set of users of a social networking platform, wherein the data reflects endorsements of pages hosted on the social networking platform. A subset of the users within the set is identified by excluding users in the set with characteristics that do not match filter criteria. For each of some of the pages endorsed by members of the subset, a measure of the likelihood of a user in the subset endorsing the page relative to the likelihood of other users in the set endorsing the page is calculated. One or more content items are selected based on the measures and data specifying the selected content items is transmitted.