In one embodiment, a method includes collecting communications from a plurality of sources. The method further includes selecting a set of topics and a set of users. In addition, the method includes, for each user, identifying, from the collected communications, conversations in which the user has participated. Moreover, the method includes, for each topic, for each user: measuring a proportion of the identified conversations that contain content suggestive of the topic; analyzing timing of the identified conversations; and examining relationships among data attributes of the identified conversations. Further, the method includes generating multidimensional expertise data. The multidimensional expertise data is representative of the user's expertise on the topic. The multidimensional expertise data includes a topical dimension, an expertise-scope dimension, and a timeline dimension. The method also includes, for each topic, ranking the set of users by expertise index. Also, the method includes providing a searchable interface.