1. A computer-implemented method, comprising: identifying a reference resource and a contextual profile for the reference resource; determining that relevance feedback data for the reference resource has at least a threshold level of similarity to the contextual profile for the reference resource, the determination being based on a difference between the relevance feedback data and topics specified by the contextual profile, the relevance feedback data specifying one or more topics that users have identified as relevant to the reference resource; in response to the determination, computing, by a data processing device, a first contextual profile for a different resource based on the contextual profile for the reference resource; and providing the first contextual profile to a processing system that is configured to identify the different resource as relevant to at least one topic from the first contextual profile when at least one topic value in the first contextual profile meets a topic value threshold for the at least one topic, wherein: identifying the contextual profile for the reference resource comprises: identifying topic values for topics to which content of the reference resource has been identified as relevant by a clustering system; and identifying data specifying a cluster topic for a cluster to which a vector of terms for the resource is identified as relevant.