Abstract. We study the exchange of information in collective information systems mediated by information agents, focusing specifically on the problem of semantic interoperability. We advocate the use of mechanisms inspired from natural language, that enable each agent to develop a repertoire of grounded categories and labels for these categories and negotiate their use with other agents. The communication system as well as its semantics is hence emergent and adaptive instead of predefined. It is the result of a self-organised semiotic dynamics where relations between data, labels for the data, and the categories associated with the labels undergo constant evolution.