Participant suggestion system

A server system hosts a plurality of conversations, each having an identified set of participants. For a respective conversation, the server accesses the conversation in which a user is a participant. The server obtains a conversation profile for the conversation, the conversation profile based on information including content of the conversation and user-specific term weights for at least a plurality of terms in the content of the conversation. The server accesses a plurality of entity profiles that are based on content and/or structure in other conversations in which the user is a participant. The server compares at least a subset of the entity profiles to the conversation profile to identify a set of entities having entity profiles that best match the conversation profile, generates a suggestion for the user including a suggested entity from the identified set of entities; and sends the suggestion to the client system for display to the user.